


A Perfect Addition... Right?

by EternalQuestForGoodFics



Series: Hunter x Hunter/Assassination Classroom [1]
Category: Assassination Classroom, Hunter X Hunter
Genre: Crossover, During Canon, Gen, Implied/Referenced Child Abuse, Post-Canon, Protective Killua Zoldyck, because Killua and Nagisa, duh - Freeform, fair warning: author is a killua simp, for AssClass, for HxH, tell me what tags I should be adding because I'm new and I don't know
Language: English
Status: In-Progress
Published: 2021-02-05
Updated: 2021-03-07
Packaged: 2021-03-17 14:48:06
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 14
Words: 31,192
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29227233
Author URL: https://archiveofourown.org/users/EternalQuestForGoodFics/pseuds/EternalQuestForGoodFics
Summary: Killua ends up in the Assassination Classroom universe. Perfect for an assassin like him right? Well... not quite.  He'd have you know he was an EX-assassin and had no intention of picking up his old job. Not even if it was to save the earth (which he'd have you know he was still skeptical about).
Relationships: Class 3-E & Korosensei (Assassination Classroom), Killua Zoldyck & Class 3-E, Killua Zoldyck & Korosensei (Assassination Classroom)
Series: Hunter x Hunter/Assassination Classroom [1]
Series URL: https://archiveofourown.org/series/2196690
Comments: 61
Kudos: 202





	1. The New Transfer

**Author's Note:**

> Since Killua would pretty much one-shot all the challenges otherwise, I chose to tank his motivation (which is the most in-character canon-compliant nerf I could give him). This is going to be post HxH canon, and I'm going to be making the executive decision that Killua had his yo-yos replaced some time between where the anime ended and this fic begins. If you can't tell, I'm going by the 2011 anime.
> 
> For the AC-verse, it's some time after Ritsu joined the class and Itona was introduced (all the better to set up anticipation for our boy haha) but before Takaoka arrived.

**Summary for the Chapter:**

> Look, even I don't know who's talking; there's too many people to pick from. Just know that I'll generally name Nagisa and Karma (since I have the deepest impression of them). I remember that in the AC-verse, there were school assemblies that were "conveniently" held during 3-E's lunchtime, but I doubt that happened every day (do school assemblies happen every day? Fuck, it's only been...5-ish years since I went to school and I've already forgotten), otherwise I'd be wondering how they find time to hike up and down the mountain every day and still have time to eat.

Class 3-E was buzzing with barely restrained anticipation and nervous energy. Karasuma-sensei had just informed them that yet _another_ transfer student was going to be joining their class. Given their previous history with transfer students, they were understandably concerned with this one.

"What do you think the new transfer student's gonna be like?"

"Dunno, just hope he isn't like how Ritsu used to be."

"Huh?"

"Oh, Ritsu, we didn't mean anything bad! You were just... really enthusiastic."

They were saved from continuing this awkward line of conversation by the arrival of Korosensei. "Good morning class! As you've been told, we will be having a new transfer student joining us from now on. Please, come in and introduce yourself!"

"Huh? Oh, is the class starting?" A voice piped up from the back of the classroom, startling pretty much everyone. Somehow, none of them had even noticed the presence of the white-haired boy until he spoke up, which was... alarming. "Yo. I'm Killua. Just Killua."

Having finished his introduction, he laid back down on the desk and seemingly went back to sleep. Everyone sweatdropped.

* * *

Class went by in a blur. Normally, Korosensei would've attempted to get this new student of his to pay attention in class, but given that he could answer questions correctly when called upon (and the fact that he was a bit curious as to what the new transfer was planning), he allowed it to slide for now.

When lunch came, Korosensei once again took off to get his meal (this time it was some French cuisine they couldn't pronounce for the life of them, and probably never would, nevermind Bitch-sensei's classes). The students looked towards their new addition, a bit surprised (but relieved) at the lack of action from him. It seemed they'd finally get a normal transfer student.

Finally, it was Nagisa who mustered up the courage to approach him. "Hey, uh, Killua-kun?"

The white-haired boy stirred and blinked his eyes. It was then that the class noticed that his eyes were a deep sapphire blue. "Yeah?"

"Oh, uh, we, well that is, I was wondering... would you like to have lunch with us?"

"Hm? I guess? Not like I have anything else to do."

Everyone blinked. That was... surprisingly simple. They had expected an antisocial loner who'd brood as he bided his time while waiting for their target to return.

Killua drew a wrapped piece of chocolate he'd stored in his bag and began unwrapping it.

"Is... is that all you're eating?"

"Huh? Mm-nope, I got more." Saying this, he drew another stack of chocolate bars from the bag, causing everyone to sweatdrop once again.

"Killua-kun, you should really have some proper food." Isogai, being the ever-responsible ikemen class president that he was, attempted to persuade Killua. However, this only earned him a hiss and Killua drawing back, shielding his chocolates protectively. He damn near inhaled the chocolates he had in his haste to get them safely in his stomach (and away from any thieving hands, well-meaning or otherwise), leaving Isogai nothing to do but sigh.

* * *

"Hey, what do you think of the new transfer student?"

"Hm? Killua? Uh, I think he's alright. Better than what I expected at least."

"You think? It was kinda creepy how none of us even noticed he was in class until he spoke up though."

"I know right? Do you think he could've gotten the drop on Korosensei?"

"Huh, probably. Wonder why he didn't take the chance."

* * *

The day passed without any assassination attempt made by the new transfer student, which somehow only served to heighten the tension. He had to be planning something big. Why else would he not act for so long? Even Korosensei was starting to feel a bit anxious.

But even once school let out for the day, there was still no move made by Killua. 

It was finally as they were about to leave for the day that Terasaka couldn't take it anymore and blurted out, "Oi! When are you going to try killing that octopus?!"

Killua gave him a lazy glance, looking for all the world like a cat that was interrupted from its lazing around by a particularly bothersome fly. "Hm? Why would I kill him?"

_'DID YOU NOT GET THE MEMO?!?!'_

Even Korosensei was taken aback. After all, he was sure that all transfers would have been informed about the situation.

"I'm kidding."

Everyone seemed to be relieved, even Korosensei for some odd reason.

"I'm just not interested."

It looked like their relief came too quickly...


	2. Karma

**Notes for the Chapter:**

> I don't think I mentioned this, but last chapter Karma wasn't in class. Considering the fact he skipped school occasionally in canon for plot convenience (i.e, he wasn't in Takoaka's class), I figured I could do the same.

After that stunning revelation, Killua disappeared before anyone could come to their senses in time to question him.

Terasaka was the first to recover. His fists clenched. "Hah?! The hell does he mean 'not interested'?! The hell is he even doing in this class then?!"

Though they would've phrased it more... tactfully, most of the class held a similar sentiment.

"Now, now, Terasaka-kun. We don't know the full story here, so let's not judge him too quickly, okay?" Korosensei lectured, "Even though everyone here should be doing their best to assassinate me, perhaps he has some extenuating circumstances? Oh no, maybe he was blackmailed by the government?! But why would they do that? I must get to the bottom of this!"

And amidst an attempted stab or two, Korosensei zipped off. Everyone sweatdropped, but they were already used to their teacher's occasional absurd logic leaps. Still... the theory wasn't all that farfetched...? They did notice that their new classmate was surprisingly stealthy for someone with such eye-catching hair, so perhaps that was why he was enlisted to help?

* * *

Karma had just walked into class when he noticed the strange atmosphere. It seemed fixated on the new white-haired kid that must be the transfer student who just came in yesterday.

_'Huh. Wonder what he did.'_

Having never known emotions resembling fear, Karma sauntered up to the kid, whose desk coincidentally happened to be next to his, all while ignoring Nagisa's blatant attempts to catch his attention. 

"So what'd you do that's got everyone all wound up?"

Killua looked up from the chocolate bar he was eating. "Why'd you assume I did something?"

"Well, given our past history with transfers, and the fact that you're the only change that happened yesterday, that's natural isn't it?"

Killua grunted and continued eating his chocolate. Only after he finished did he speak, "I didn't do anything."

Karma raised a brow, intent on getting him to spill, when he was dragged away by a Nagisa who'd had enough of being ignored.

"Karma-kun, stop. He's... not _wrong_ , but..."

This piqued Karma's curiousity even more. He was about to continue asking when Terasaka slammed the door open and marched over to Killua, hollering, "You better explain yourself you little punk! The hell do you mean you don't intend to kill the octopus?!"

_'Well. That answers my question.'_

Killua's gaze landed on Terasaka, before turning away in a clearly dismissive gesture. "Do I need to simplify it for you? Does a meathead like you not understand big words? Fine, since I'm feeling generous today: I am not going to kill the octopus."

Terasaka's face was purple from rage and he was this close to snapping and grabbing Killua by the lapel when Korosensei entered.

"Good morning class! Let's get ready for a wonderful day ahead, shall we? Oh, and Killua-kun, could you stay back after class for a bit."

Killua's gaze flicked to their teacher before giving a hum of assent.

Nagisa and Karma shared a look, already on the same page.


	3. Important Conversation

**Notes for the Chapter:**

> So... the original version of this chapter got accidentally discarded (thanks mobile) which nearly demolished my resolve to write, but I figured I'd re-type while the memory is still fresh. Also, I don't keep track of chapter word counts, I kinda just write till a scene feels like it can end.
> 
> Decided to write so much recently because inspiration struck, don't have an update schedule, just riding off the high of finishing my finals combined with the severe deprivation of Killua in AC stories.

After class, Korosensei brought Killua to the teacher's lounge. Karma and Nagisa snuck off after them.

"Ne, sensei, are you talking to the other students today too?"

"No, what makes you say that, Killua-kun?"

"Well I figured since two of my classmates followed us here, you were planning to speak to them too."

Having been found out, Karma and Nagisa stepped into full view of the teacher's lounge.

"Well we had questions, so we came to ask them." Korosensei gave them a disapproving look and his patented 'red cross face'. "Karma-kun, if you had questions, you can wait till after our conversation instead of listening in."

Nagisa looked embarassed and prepared to slip away, but was caught by the back of his collar by Karma. "Karma-kun, what-"

"I had questions for Killua too."

Just as he was about to get another lecture on privacy and respecting boundaries, Killua interjected, "Well, it's not like my answer would change even if they weren't here. So, meh, do whatever."

Now that Killua had given permission, Korosensei could only continue on with his planned conversation (though none of his students needed to know said plan was already in tatters thanks to the extra audience).

"Killua-kun, I wished to ask you for the reason you refuse to participate in the assassination."

An unreadable look entered Killua's eyes, but soon faded, giving way to his default calm. "Personal reasons. Just take it as if I believe killing is wrong."

"While that is an admirable principle, would it not be immoral to stand by while others die due to your inaction?"

"Oh, you mean the whole destroying the Earth deal?"

Korosensei nodded, so Killua continued. "There's been something bothering me about that. I know about your deal with the government and the bounty on your head. My question is: why go to so much effort just to teach a class that would normally be ignored and overlooked?"

At this, Nagisa looked down, while Karma looked intrigued to see where this was going. Korosensei was about to give an answer, but Killua continued speaking, "Out of the goodness of your heart? Well let's say that your moral values allow for both destroying the Earth and uplifting a downtrodden class. But that still leaves the question of why this class? You could've picked any class from any school in Japan, heck, the world, and you pick this one? Fine, that can be excused with the secrecy the environment provides, or at worst random selection, but it seems like you're investing a lot into a class that will likely not manage to kill you before your deadline and would thus end up blown up along with the rest of the planet."

"Now, Killua-kun, you shouldn't come to conclusions so soon; you've only been here a day-"

"I wasn't finished. Let's say this is all an elaborate suicide attempt where you'll end up going easy at the last moment, thus allowing your students to kill you-" At this, Korosensei started sweating internally. "-but why pick this method of 'suicide' in the first place? If you could get to the moon to destroy it, then why not just fly into the sun? Why pick a method that would undoubtedly place a burden on your students' consciences if and when they succeed? From what little I've seen of you so far, you appear to be a model teacher-" At this, Korosensei blushed. "-who just wants his students to succeed, so why potentially saddle them with guilt and possible trauma?"

At this, Karma and Nagisa seemed to think it over. While logically, they had known they might end up with (even more) issues from killing someone, it had always felt... abstract. Unreal. As if it was difficult to conceptualize, which was what had kept them from really thinking about this in detail, but Killua's words seemed to have broken that barrier. They had a lot to think about.

Korosensei was about to defend himself, but Killua continued his onslaught; he was on a roll now. "The only explanation is that this is not a suicide, at least, not entirely, but a genuine attempt to teach. And I'm pretty sure the government would've deduced that much, given that _you_ approached _them_.

But as a result, this class has essentially been placed in the line of fire for any potential outside assassination attempts. In the face of immediate danger and possible future danger, it's only natural for kids to run off right? Well, that's where the bounty comes in. It acts as the 'carrot' to the 'stick' of possible danger so that you won't run off if all your students leave.

They want you to stay where they can predict your whereabouts so they can properly plan an assassination attempt with a higher likelihood of success. Of course, the bounty also serves a dual purpose in that it attracts assassination attempts on your life, thus providing a good distraction for whatever's being planned."

Silence befell the room. That... was way more than they'd expected the white-haired boy to say. And more detailed too. At last, Korosensei had the chance to speak. "That was an excellent analysis, Killua-kun. Are you sure about not taking part in the assassination? With your skills, I'm sure you'd make a fine assassin."

At this, something flashed in Killua's eyes but was gone in an instant. He shoved his hands in his pockets, feigning nonchalance. "Nah, I'll pass. Just putting it out there that I'm not going to make any conscious attacks or give my classmates any plans to follow. But anything they come up with on their own has nothing to do with me."

_'Is... is he saying he might feed us info? If they're all as detailed as what he just said...'_ Nagisa thought.

Korosensei spoke, "I'm just worried about the schism that might form between you and your classmates if you outright refuse to help them."

Killua shrugged. "It's not like I particularly care."

Korosensei looked ready to launch into a lecture on the benefits of friendship and getting along with your peers but was cut off by Killua. Again.

"Well, I mostly phrased it that way to piss off the dumb oaf, so if they wanted me to say, stand somewhere looking distracting... I take payment in chocolates."

Nagisa sweatdropped. _'So that was all a ploy to get more chocolate for himself? Why am I not surprised?'_

The smile on Karma's face was bordering maniacal at this point, as if he had just found an interesting new plaything.

At this point, Korosensei knew that was all he was getting out of the white-haired boy. "Alright, Killua-kun. So, I was also wondering how you're finding your time here? Is there anything you don't understand or need more help with?"

This time Nagisa did actually manage to drag a surprisingly unresisting Karma out, having caught on that this was information that Killua might not feel comfortable sharing with them around. He still managed to hear Killua's response though.

"Hm, it's okay I guess. Just different from what I'm used to. I'm doing alright in everything I suppose, though recognising some of the tougher kanji is pretty hard."

_'Huh, that's weird. The kanji we're using is pretty standard for our level? With Killua's smarts, I would've assumed he wouldn't have problems with it... Is he a foreigner? Can't tell from the way he speaks but...' Was what Nagisa thought._

Meanwhile, Karma was contemplating ways he could use to wheedle more information from Killua. For all that he'd said, he hadn't actually revealed much about himself but something told Karma the blue-eyed boy was one to look out for. He grinned.

**Notes for the Chapter:**

> I don't know if the analysis I had Killua give was a good one or if it's shot full of holes. Was it out of character? Bitch he gave a fucking lecture on how he avoided death to an enemy he just incapacitated WHILE BLEEDING OUT. The little dumb genius can really talk.
> 
> Anyway, please give me feedback, it's the driving force behind most authors' motivation. And motivation = chapters.
> 
> Kudos, comments, any kinda feedback would be good.


	4. Teachers

**Summary for the Chapter:**

> Newbie teacher Korosensei consults his coworkers (who he conveniently forgot have LESS teaching experience than he does) about the Killua problem.

**Notes for the Chapter:**

> Did I forget to mention Karasuma and Irina? Why, yes, yes I did. So I came up with a flimsy excuse as to why they were gone for yesterday, don't look too closely.

Korosensei fretted. This wasn't an uncommon occurrence for him, but usually he wasn't fretting about someone _not_ wanting to kill him. During his talk with Killua, he had tried to probe deeper into the reasons for his reluctance, but the topic usually got re-directed (usually so subtly he didn't notice until a good while after being distracted) or he got blunt answers that told him nothing more than what he already gleaned. It didn't help that he couldn't really get a good read on this new student; during the amount of time they knew each other, all Korosensei got about his personality was that he was that he was very sharp, in both academics and general analytical ability, but didn't have much motivation to use it. Oh, and that his love for chocolate could contest the teacher's own love for sweets.

It was during his restless pacing that he heard the door open, heralding the return of his coworkers. They had left yesterday on urgent summons by their superiors (well, _Karasuma_ had. Who knows what Irina was up to?) and so missed the arrival of the new transfer and the surprises he brought.

_'Perhaps a fresh perspective will be just what I need?'_

Thinking thus, Korosensei's eyes lit up as he started fawning all over the two, who immediately sensed something fishy. Or, well, octopusi? 

"Alright, spill. What do you want, _target_?" Karasuma got straight to the point in his usual no nonsense manner, while Irina continued her futile attempts at stabbing Korosensei.

"W-well, it's the new student. I'm worried."

"Oh? Is he actually close to succeeding?"

"No, it's the opposite problem; he doesn't _want_ to kill me!"

At that, both of the other teachers froze in surprise. They really hadn't been expecting that; after all, transfers to this class had to be vetted by the government beforehand and/or be specially sought out for the purpose of the assassination beforehand. So to say that this one didn't want to...

_'Perhaps it's to get the target to lower his guard?'_

At this thought, Karasuma collected himself. But Irina clearly hadn't had the same thought. "What? Why not? Who even let him join the class if he refuses to do the job?"

Korosensei bit on his hankerchief. "That's the thing; I'm not sure he's here willingly. Do you think you guys could er, pull some strings to make sure he isn't being coerced into my class?"

At that, he started muttering to himself about how terrible it would be if the poor boy was forced into this, and/or plans about how to convince him to join the assassination. Karasuma wasn't sure which, but he ignored his coworker-slash-target's usual theatrics with practised ease. He turned to Irina. "Can you observe him in your class tomorrow? I'll see how he is during PE."

Irina agreed. She too was curious about this new transfer.

* * *

The next day, during the break they had before their English class for the day, the students were chatting in little groups. Well, save for Killua, who was mostly just listening in. It was at that point that Karma sauntered up to him. "Hey, what's up?"

Killua was currently eating a chocolate bar, so he could only give a muffled reply combined with what looked like a shrug.

"Just a heads up, we're having a different teacher for English today. We call her Bitch-sensei."

Killua stopped eating for a moment, blinking in surprise. He finished up the chocolate in rapid bites so that he was free to talk. "Why?"

At this, Nagisa, who had been trailing behind Karma, interjected. "Because she was, uh... pretty rude when she first joined. She's a pro assassin that specialises in... charming her targets."

Killua looked contemplative for a moment. "Thanks for the warning. Now what do you want?"

Karma raised a brow. "What makes you think I want anything?"

"Intuition. That and you don't seem like the type to give out information for free."

"What? Can't I just get to know my new classmate?"

Killua eyed him suspiciously.

"Besides, I wanted to know if you'd want to hang out after school."

_'Ah, there's the catch.'_

Killua appeared to think over this for a bit. "I guess? Though if you get into a fight, I'm not helping."

Karma seemed mildly surprised that Killua already knew of his reputation for getting into fights, but after a moment of thought, he figured that it wasn't too hard to find out.

"Sure, see you after school then?"

Once he got the nod from Killua, he turned to head back to his desk, satisfied. Nagisa, meanwhile, seemed hesitant. Killua cocked an eyebrow, as if to ask why he was still there. "That, uh... about the teacher, she can uh, be really touchy-feely. Like, _really_ touchy-feely."

Killua didn't seem to get it for a moment, but when he did, his eyes widened slightly and he muttered something under his breath that Nagisa could've sworn was "not another damn pedophile", but he figured his ears probably weren't working right.

"Thanks for the warning I guess. I take it you've experienced it firsthand?"

Nagisa grimaced, and was about to say something, when the subject of their conversation walked in, prompting Nagisa to give Killua an apologetic look for having to cut short their conversation, and returned to his seat.

Irina's gaze roamed the classroom before landing on the new tuft of stark white hair at the back of the class. Smirking, she sauntered over. The closer she got, the more Killua's hackles raised. Just as she was about to touch him, he grabbed her wrist. "Don't enter my personal space."

She raised a brow. She was a bit tempted to continue, but a little voice at the back of her mind told her not to antagonise him too much as she was still unaware of how capable and/or dangerous he was.

"Just checking out the new student." She purred, causing Killua to have to suppress shudders.

Fortunately, the rest of the lesson went by without a hitch, albeit with the usual levels of discomfort from Irina's usual risque method of teaching.

* * *

When it was finally time for PE, most of the class were curious to see how skilled Killua was with a knife, seeing as he hadn't so much as drawn the anti-Koro knife he'd been given. Yesterday, PE had been of a more garden variety where everyone did normal exercises, seeing as Karasuma-sensei hadn't been around to supervise, so today would be the first chance they'd get to see how Killua was in a fight.

Karasuma was, though he'd never admit it, also mildly interested to see what the white-haired boy had to offer.

The only one who appeared completely unfazed, even when told the change in curriculum from yesterday, was Killua.

They first went through their normal warm-up knife routine. The class was a bit disappointed to find that, though Killua was executing it flawlessly, it was just the normal routine they all went through. Karasuma, on the other hand, could tell that Killua's movements were fluid and certain, as if every action was carefully deliberated, but in a manner that implied it was mostly on instinct. He filed that tidbit away in the back of his mind.

After the warm-up, he called Killua and Nagisa out to spar with him. The reason he chose Nagisa was because he wasn't the best, nor the worst at using a knife, and so he'd be able to gauge Killua's abilities with some form of benchmark. What he hadn't expected was for Killua to mutter in Nagisa's ear for a bit before taking on a fighting stance.

Karasuma's brow furrowed. _'What did he say to Nagisa?'_

Killua was positioned slightly to the right in front of Karasuma, while Nagisa had taken the left. At first, Karasuma was able to divide his attention between them equally, but as the match went on, it seemed Nagisa drew back a bit, appearing out of breath, while Killua continued nonchalantly harassing him with attacks. Though none of the attacks landed, Karasuma was unable to get a solid hit or hold on Killua. In fact, Karasuma felt like Killua was holding back. This fact caused him a bit of irritation, making him divert more attention to getting Killua to fight more seriously.

Killua seemed to take on a more playful vibe, but unlike Karma, who simply enjoyed the fight, Killua appeared more like a cat toying with its prey. Every time Karasuma got a chance to take a slight breather, he'd press forward again, and every time Karasuma went on the offensive, Killua would somehow manage to mess up his rhythm. It was frustrating. So frustrating that the sudden spike of bloodlust from behind startled him enough that Killua was able to kick him square in the chest and towards the source of bloodlust. In that moment, he attempted to use his momentum to disarm Nagisa, who had gotten behind him at some point, somehow without him noticing (though he had a pretty good idea of how that happened), but this left him open for Killua to come at him from the side, and grab his left arm, holding it behind him while pointing the fake knife at his neck.

Just as Karasuma was about to grab him with his other arm, Nagisa pointed his knife at Karasuma's chest. The fight was over. In a real fight, Karasuma wouldn't have the time to both get Killua and Nagisa's knives away from his vitals in time. "Alright, that's enough. Match is over."

Killua released his arm and stepped back, Nagisa following his lead. Karma's hands had started twitching with the need to test himself against his new classmate, a demented grin growing on his face. For a moment, the rest of the class was silent as they processed the fight they had just witnessed. Then, everyone erupted into applause and muttering amongst themselves.

"That was so cool!"

"Even I didn't notice Nagisa got behind Karasuma-sensei! Wow!"

"Woah, Killua, didn't know you could fight like that."

Killua appeared a bit out of his element with all the encouragement, and so could only turn away from them, looking back at his teammate. "Nice job."

Nagisa also appeared a bit stunned that they had actually beat Karasuma-sensei, "Y-yeah, you too."

Karasuma dusted himself off and eyed the white-haired teen. "I didn't expect the two of you to work so well together. How did you know Nagisa could do that?"

Killua rubbed the back of his head. "A hunch. And it was mostly Nagisa anyway, since he had to act tired enough for his presence to not register for you."

Nagisa looked at him, surprised that he was getting the credit. 

Karasuma's eyes narrowed almost imperceptibly. _'He's drawing attention away from himself huh? It's so I won't question why he didn't go all out, isn't it?'_

He considered doing so anyway, but decided not to. He was pretty certain Killua wouldn't clarify, so he decided he'd pose this question, among others, to his superiors.

**Notes for the Chapter:**

> Thanks for all the comments. They really motivate me. Also, Irina really dodged a bullet there.
> 
> I was initially going to place the timeline before the baseball match, but then I realised I know fuck-all about sports rules in general, so I placed it after. Both work. Just know that Takaoka hasn't showed up yet ;)


	5. Takaoka

**Summary for the Chapter:**

> You know who I'm talking about.

**Notes for the Chapter:**

> It's been a while since I watched AC, so I've had to keep a separate tab open to see how canon flows, then think of how to fit in the changes I made in this AU. I tried taking out excerpts from the episodes at first, word-for-word, but then figured that all of you reading this have probably already watched the show so I could just paraphrase and summarise (that way I don't have to think too much on Takaoka 'call-me-Daddy' Akira and his cringe af lines)

After Killua and Nagisa's match was over, Karasuma paired off the other students to practice with each other while allowing them to make attempts at attacking him. He kept Killua and Nagisa together though; it was easier than coming up with a new pairing.

As Karasuma gave pointers to the students closer to him, he saw out of the corner of his eye that Killua appeared to be doing the same with Nagisa. Huh. He filed that away too, and continued noting the strengths and areas of improvement for the other students.

Nagisa panted as yet another one of his attacks was skillfully evaded by his opponent dancing out of the way like he did with Karasuma. He could now empathise with why his teacher had put more focus on Killua; it was simply too hard to attack and defend against the other boy otherwise.

"Your, your plan just now was great." Nagisa got out between pants, since Killua didn't seem as intent on attacking him as he was with Karasuma, he had the time to talk.

"Hm? I guess. You went along with it pretty well though, considering it was our first time working together."

"Yeah. I think you're a natural leader, Killua-kun. I didn't even think before I followed your instructions!"

That startled Killua enough for Nagisa to launch an attack that got the closest to hitting the other boy he'd gotten. _'Note to self: possible weaknesses include being unused to compliments?'_

"Uh, yeah. Guess I'm used to it."

Now that caught Nagisa's attention. He thought that with the other boy's personality, he'd be more of the loner type. He wouldn't have pegged him to be a leader. He didn't mention it though, since Killua had renewed his onslaught after that, and it was all he could do to defend himself.

"You work best when you have the element of surprise, but struggle when it comes to head-on combat. You should work to your strength; if this was a real fight, you should always keep an eye out on your surroundings to find opportunities to turn the 'fight' back into an 'assassination'."

Nagisa was startled by the sudden pointers he was being given, but made a mental note of it anyway.

* * *

By the time the bell rang, signalling the end of class, Nagisa was ready to collapse, while his sparring partner hadn't even broken a sweat. _'He's got some crazy stamina...'_

"Man, Killua and Nagisa made it look easy, but getting a hit on Karasuma-sensei is really hard!"

"Sensei!" Kurahashi approached him.

"Come out for snacks with us after class!" She invited. But their teacher waved a dismissive hand. "I appreciate the invite, but I still have work to do."

Some of the class visibly deflated at the rejection. "Hard to get close to him in his personal life too. Man, it's like there's a wall between us."

"Is he only taking care of us because he has to?"

Suddenly, a new voice called out from the direction of the building, "Yo! Karasuma!"

Karasuma's eyes widened. "Takaoka!"

The person referred to as "Takaoka" was a slightly portly, but still burly man with a slight undercut. He was currently lugging around a bunch of what looked to be shopping bags and boxes. He addressed the class with a bright smile, "Hey! I'm Akira Takaoka, and I'll be assisting Karasuma as of today! Nice to meet you, E-Class!"

* * *

Karma felt like leaving the moment this new teacher showed up. This guy reminded him of his old teachers back at the main campus; in other words, the type of teacher he detested the most. He caught Killua's eye and waved in a wordless invitation to leave with him, but it was then that Takaoka took out the big guns- chocolate (amongst other sweets). Killua, who had appeared to be about to join Karma, immediately zeroed in on the snacks.

Karma sighed. He had a feeling he wouldn't be able to pull the sweet-toothed boy away any time soon, so he shrugged and walked off to do his own thing for a bit before meeting up after school to hang out.

Meanwhile, Killua had snagged a few of the more chocolate-covered items on offer and walked off to enjoy them in peace. He was soon followed by Nagisa, who seemed to have latched on to the other teen for some reason even he couldn't name.

"The new teacher seems like a nice guy."

"I wouldn't trust him as far you could throw him. He gives me a bad vibe. Pretty sure Karma think's the same, seeing as he's walked off."

Nagisa eyed Killua, who was eating the dessert in his hand with vigour. "And yet you still ate the snacks he brought?"

"Hey, chocolate is chocolate. Besides..." Killua trailed off.

"What?" Nagisa was curious.

"Nothing really." Killua brushed off the question like he did so many others, so Nagisa filed it under the mental folder he labelled 'things that may or may not relate to Killua's past'.

"Say, you and Karma look pretty close, yet not at the same time. What gives?"

Nagisa tilted his head. "What makes you say that?"

"Well, seems like you guys are pretty comfortable with each other during class, but I haven't seen you hanging out with him afterwards. And when you speak to each other, there's this air of familiarity, as if you guys knew each other for a bit."

"Oh." Nagisa fell silent. "To be honest, I don't really know either. We used to hang out before, but one day he just stopped hanging out with me outside class, and now it seems we're more like normal classmates."

Killua raised a brow, but made no further comment as he continued to enjoy his snack.

* * *

After class, Killua waved goodbye to Nagisa and waited at the school gates. It wasn't like he knew where else to meet up with Karma, and he didn't have a way of contacting the redhead. After a few attempts at harassment by the other students though, he hid up a tree and concealed his presence.

After about 5 minutes of waiting, just as he was getting bored, he spotted the bright red hair of his classmate. Once he verified that it was indeed Karma, he leapt down from his perch, startling Karma. "What were you doing in that tree?"

"Other students were being annoying." Killua stated. Just from that, Karma understood what the white-haired kid was trying to say. It really was quite annoying having to deal with main campus pricks.

"So, what are we doing?" Killua asked, hands in his pockets.

Karma shot a question back at him, "What do you want to do?"

"What's there to do for fun around here?"

Karma turned back around to look at him, only now noticing that Killua had taken one of his hands out his pockets and was currently playing with a yo-yo.

He raised a brow, only to get a challenging look back, at which he raised his arms in mock surrender. "Well we could always hang out at the arcade I guess. Say, how good are you at arcade games?"

Killua appeared to ponder for a moment, before replying, "Dunno. Never really went to one."

At that, Karma halted in his tracks. "Woah, seriously?"

"Yeah."

Karma was now determined to rectify this tragedy and introduce his new classmate to arcades (and hopefully beat him at some of the games so he could gloat).

* * *

The two ended up in a contest of sorts (naturally, it was Karma who came up with the idea) where for every win Karma got, he'd have the chance to ask a question that Killua would have to answer, while if Killua won, he'd get one chocolate bar for the first game, and an additional one to the one bar for winning for each subsequent game (pretty much the result of Killua's haggling).

Naturally, with this kind of motivation, Killua ended up winning four of the five games, only losing the first one due to his inexperience with the controls. Hugging his ten chocolate bars to his chest smugly, Killua asked Karma, "So, what'd you want to ask?"

They had agreed to wait till after they exited the arcade to talk as it was really loud inside.

Karma looked kinda depressed; he thought he'd be able to win more. Since he only had the one shot, he had to ponder his question more carefully, so he remained silent for a full minute before deciding on the one that he was both the most interested in as of that moment as well as the one Killua was likely to answer in depth. "How much were you holding back against Karasuma-sensei?"

Killua was silent, likely thinking about how to answer without revealing too much. "Mm, well I wasn't even using half strength."

Karma cocked a brow. "Could you be a bit more specific?"

Killua chewed his bottom lip before taking out the yo-yo from before and holding it out to Karma. Curious, the latter reached out his hand to take it from him, but Killua didn't release it fully. It was a good thing he didn't too, for Karma wasn't prepared for the surprising weight that no one would've expected of such a small yo-yo.

"Holy shit, how heavy is this thing?"

"About 50 kilos, give or take."

Karma thought his jaw had dropped, which would be a first. _'This kid is just casually toying with something that weighs 50 kilos like it was a regular yo-yo? Wow, he really was holding back. Dunno if Karasuma-sensei could've handled a full force punch from someone with that strength...'_

At this, his smile stretched into a demented caricature of its normal state, causing Killua to inch back slightly, eyeing him warily, (unfortunately) all too used to the type of psychos those smiles usually belonged to.

"Man, I really wanna fight you now."

_'Yup, that kind of psycho alright.'_

* * *

The next day, during PE, all the students (save for Karma) were gathered on the field in formation. Killua was there too, but he looked bored out of his mind, as if he could take off at any moment. Then again, that was his default expression and he hadn't skipped class once... Huh. 

When Takaoka promised more of the sweets from yesterday, he perked up, but kept his ears open for the 'catch'. And once Takaoka took out their new training schedule... well, he could see the catch now. Still, wasn't as bad as what his training schedule used to be like. But from the reactions of his classmates, it appeared that this amount of training was _not_ acceptable for a normal person. So kept silent. Right up until the point he felt the atmosphere change when Maehara was complaining about it.

At which point he spoke up, "Baka. Ever heard of progressive intensity?"

Takaoka's attention was immediately switched to him. "Oh? Care to enlighten your old man?"

Killua's eyes narrowed, his hands in his pockets, "You deaf?"

At this point, Takaoka had made it to Killua and now loomed over the boy. "Why don't you elaborate for me?"

"That's why you're an idiot-" Killua was interrupted by being kicked in the midriff and sent flying, shocking his classmates. Nagisa was about to rush over to check on him, but noticed that Killua hadn't even taken his hands out of his pockets, and so hesitated, wondering if he should risk catching Takaoka's attention and ruining whatever plan Killua might have. Because if there was one thing he'd learned about the other kid, it was that he usually had a plan.

He was proven right when, after Takaoka was distracted with intimidating the rest of the class into obedience, Killua leapt to his feet, appearing completely unfazed by the hit. But before he could do anything, Karasuma rushed onto the field. To understand why he came out earlier this time, let's go back in time a bit shall we?

* * *

In the staff room, Karasuma was sorting out the new paperwork he was saddled with when he got an email notification about a subject he'd set to high priority. He had sent an inquiry about the new transfer student and wasn't expected a reply so soon, but when he opened the email, all contained was a basic file with a description of his appearance but not much else. Also of note was that it was labelled with "DO NOT ANTAGONIZE." Whereas for Ritsu, he had the label had been "ASSIST WHERE NECESSARY" and Itona's had been "DO NOT INTERFERE," Killua's label worried him because it implied that he was far more dangerous than the other two.

It was due to this that he didn't dwell in his head about whether Takaoka's teaching methods were better than his, nor did he pay much mind to Irina talking to him. Instead, when a new email came in, this one set on a lower priority, and so would've probably been missed for a while had he not been checking his emails. He opened it, and after scanning all the photos, his eyes widened and he rushed out of the classroom.

* * *

Back to the present, Karasuma had emerged from the building in time to watch Killua get sent flying, and all he could feel was blood rushing to his head between concern for a student and concern because a student who had been clearly labelled "DO NOT ANTAGONIZE" had clearly been very antagonized. It was this that had him rushing over before any more 'casualties' resulted because of Takaoka's heavy-handedness. Out of the corner of his eye, he noticed Killua get up, but didn't seem like he was about to attack, so he put him out of his mind for now, and instead addressed Takaoka, hoping to keep the other man from attacking the other students. "Takaoka, stop!"

"Stop what, Karasuma? I was just disciplining some of my unruly kids, isn't that right?" He turned to the class, a demented smile on his face. So focused was he on the rest of the class that he missed the fact Killua had disappeared from the spot where he landed.

It was at this point that an enraged Korosensei showed up and attempted to intimidate the other man, but was rebuffed, so he could only leave this matter in the hands of Karasuma, as reluctant as he was to do so. Karasuma still appeared indecisive, but when Takaoka nearly hit another one of his ~~kids~~ students, he stepped in. "That's enough. If you want to get violent, you can get violent with me."

Takaoka grinned slyly and told Karasuma to pick one of his students to fight him with a real knife instead, to see who was better at training assassins. Now, Karasuma was about to pick Killua (he could spot a hint of white at the edge of the woods; seems like Killua had gone off to hide), given that the snowy-haired teen could definitely hold his own in a fight, but the kid had just gotten kicked in the gut and he felt like asking him to fight after that would be pretty unfair. Then, he remembered Nagisa.

He was the one who offered the knife to Nagisa, but even he was shocked when the boy accepted it.

Meanwhile, Nagisa was feeling a bit nervous. He definitely couldn't hold his own as well as Killua, but he had to try. Thinking of the white-haired teen brought forth the advice he'd given him the day before: _You work best when you have the element of surprise, but struggle when it comes to head-on combat. You should work to your strength._

_'That's right! I don't have to win a "fight", this is an "assassination"! I just have to "kill" him before he touches me.'_

Following Killua's advice, he calmed himself and came up with the strategy he was going for.

When Nagisa took down Takaoka in one swift, fluid motion, pretty much everyone (save for the blue-eyed gaze coming from the forest, as well as Korosensei) was stunned. The fight was over, just like that.

* * *

Of course, Takaoka refused to take this loss lying down, and would've attacked Nagisa had Karasuma not defended him and flipped the bulkier man to the ground. By this point, Killua had emerged from the woods and had silently made his way to Nagisa's side.

It was at this moment that the Principal made himself known and shoved Takaoka's dismissal notice down his throat. Literally. Killua would've applauded had he not sensed that it would be a bad idea to get the attention of this man.

When he heard they were going out for sweets, his eyes lit up, and he easily accepted whatever apology Karasuma was trying to direct towards him for not stepping in on time.

* * *

After the class had dispersed, Killua trailed along behind Nagisa, which got the latter curious as the former usually disappeared after the class disbanded after school. "Guess I should say thanks for avenging me."

Nagisa blinked.

"You wanna go get some more chocolate?"

Nagisa deadpanned.

Noticing the look, Killua reassured him, "Don't worry, it's my treat."

Nagisa looked at him as if he was an impostor. In what world would Killua treat someone else to chocolates with his own money? The answer: not this one.

"Hey, I got an unexpected windfall today, so why not?"

Saying this, he pulled out a familiar-looking wallet from his pocket. At first, Nagisa couldn't place it, but then he recalled seeing it in Takaoka's hand yesterday when he'd jokingly said he emptied out his wallet for the snacks he bought...

Nagisa looked him dead in the eyes. "Did you bait him to attack you just so you could pickpocket him?"

"Yup."

**Notes for the Chapter:**

> Yes I was inspired by Killua vs the Amori Brothers. I swear, it feels like I'm writing progressively longer chapters, but honestly I didn't want to split this one even though I probably should've. I just don't really like having chapters with the same name since as a reader I could never tell how many more chapters of it the author would post and it drove me nuts.


	6. Terasaka In The Bathroom

**Summary for the Chapter:**

> Terasaka: Oh, so when I do it, I'm being whiny, but when that guy *points at Killua* does it, he's just cool?!
> 
> Killua, looks up from his chocolate, thinking: The hell is he even talking about?

**Notes for the Chapter:**

> Yes, the title is a reference. Got inspiration from an AC reaction fic on wattpad. My god, I'm on a roll. Here's to hoping I don't burn out on this fic. Though if I do, at least I can come back in a few months/years and have a story practically tailor-made for my tastes that will feel new-ish thanks to my shitty memory? Positive thoughts.

Once Nagisa had gotten past the surprise (though really, why did he even bother anymore?), he declined Killua's invitation, citing the need to be back home by curfew.

Killua shrugged. "Suit yourself. More for me."

He probably should've expressed some concern over the fact that his classmate _had_ technically stolen a wallet, but given that Nagisa himself did scare the crap out of said victim, he felt like he had no room to talk. So, instead he asked another question, "Does it still hurt?"

Killua blinked. "Does what still hurt?"

"Your stomach. From when Takaoka kicked you."

"Oh, that. Nah, I've taken worse. Honestly the landing hurt more and I barely felt that."

Nagisa's mind whirled. That was more information than he'd gotten from Killua in one go before, and yet still he felt like it wasn't enough; it was as if he given a key but couldn't find the lock that it was meant for. He also had the niggling suspicion that creating an opportunity to pickpocket Takaoka wasn't his only motivation for speaking up back then. After all, it was a bit conveniently timed. Nagisa hadn't been able to put a name to it back then, but he had this hair-raising feeling at the back of his nape when Maehara was talking, almost as if Takaoka had been about to attack Maehara. And considering his actions afterwards, he could definitely confirm that was what Takaoka had intended. Now the question remained: had Killua also sensed it, and decided to re-direct the aggression towards himself? Nagisa doubted Killua would give a straight answer.

So lost in his own thoughts was he that it was only when they almost reached Nagisa's house that Nagisa realised that Killua had been walking him back home, which seemed out of character. Wanting to keep his new friend (?) from interacting too much with his mother (Nagisa knew his mother could be... _intense_ with his male friends, much to the dismay of poor Sugino who had been the particular friend in question to find out), Nagisa tried to dissuade Killua from following him any further.

Killua gave him a look, cocked his head to the side slightly as if considering his request, before acquiescing.

What Nagisa didn't know was that Killua continued tailing after the blue-haired boy from a distance. Only once he was certain the other boy got home safe did he turn to leave, but he couldn't help but catch snippets of conversation by the blue-haired woman, who must be Nagisa's mother, that concerned him slightly. He hesitated, wondering if he should try to interfere. In the end, he decided not to, as Nagisa wasn't in any immediate danger and would probably be pissed that Killua had not only followed him, but also eavesdropped on what was supposed to be a private conversation with his mother.

This did result in Killua settling on the idea he had floating around since yesterday though... Well, that'd have to wait for next week.

* * *

Monday was a sweltering hot day, which was to be expected really, given it was going into summer at this point. The heat situation wasn't helped by the fact that the old campus building had no air conditioning whatsoever, so the students had to suffer through their lessons in the stifling heat. As a result, pretty much no one was paying attention to classes today, no matter how much they tried to focus or how much Korosensei tried to get them back on task.

In the end, it seemed as though Korosensei gave up and released them for an early lunch break before zipping off, which normally would've raised questions but no one was in the right frame of mind to be thinking clearly. Even Killua was sipping on a juice packet instead of munching on his chocolates like usual; it was just too hot for chocolate. It was only towards the end of lunch break that Killua remembered about his plan to approach Nagisa last Friday. However, he was unable to do so as it was at this moment their teacher came zipping back in the classroom and declaring he was taking them out for an impromptu field trip.

Everyone groaned, not wanting to be outside where it'd be even hotter, but listened to their teacher anyway.

* * *

A pool. Their teacher had built an entire pool during their lunch break.

Immediately, everyone seemed to liven up as they jumped in with wild abandon. Well, everyone except Killua. Bodies of water with other people in it? With his nen? No way. That was just begging for an accident to happen. Even if he had good control over his nen, if someone managed to startle him, he'd be revealing his ability to the whole class.

So, instead of joining the class, he decided to hang back in the shade and say he didn't like crowds and bodies of water mixing (which technically wasn't a lie; that _was_ his core reasoning). It wasn't like he was the only one to stay out of the water either; Hazama was just chilling by the banks and reading a book, while Terasaka was... huh, was he sulking and stalking off?

Killua blinked at Terasaka's retreating back. _'What's his problem?'_

* * *

Killua had snuck off while the rest of the class was busy trying to splash their teacher with his newly discovered weakness (water) and decided to cool off in a secluded pond. One _not_ filled with people who could be electrocuted. He could bear the heat; he'd been put through worse conditions during his training, but why subject himself to unnecessary discomfort?

Given that he had a little base on the mountain itself (that he doubted even his teachers knew about, since he went out of his way to look like he came from off campus), he had explored this mountain quite a lot, and knew where to find the nice spots to hang out. Sure, he had an _actual_ apartment that had been given to him by the government, but since it was from the government... well, let's just say there were so many cameras in it, it could put a reality TV set to shame. So, he really only went there to grab some groceries they provided. He tended to change where he was staying often, since he didn't want to be tracked.

Being in the wilderness like this reminded him a lot of his time on Whale Island, which never failed to bring forth a wave of nostalgia, and the pang of loneliness of knowing the person who he'd spent the most time with during that period was out of his reach right now.

_'Man I miss Gon. Wonder how he's doing?'_

* * *

When Killua got back to class, he was just in time to catch Terasaka kicking over Korosensei's motorcycle replica, causing much distress to the octopus and raising the ire of his classmates. _'Not really sure how they're planning to kill someone they're clearly so attached to.'_

Even Killua was stunned when Terasaka threw down the canister of... whatever it was. Killua didn't really _know_ about tantrums firsthand (given the kind of family he grew up in, all the kids knew better than to do something so futilely juvenile), but he had seen some toddlers throwing fits in public before. And yet, even they seemed put to shame by this display. When Killua voiced this thought out loud, Karma, who was the only one standing close enough to hear him, felt a laugh escape his mouth.

Killua walked over to the canister and picked it up. Karma came over too, having had his attention drawn by his white-haired classmate's comment. Killua inspected it, and frowned when he couldn't find a label. He didn't usually pay attention to laws and stuff, but he was pretty sure canisters had to be labelled before being sold. Which was why it was so weird that this one was completely blank. Karma frowned too, having had the same thought and was pondering the implications when they were called back to class.

* * *

After classes ended, it once again occurred to Killua that he ought to pull Nagisa aside now, else he'd have to wait for tomorrow.

When he found Nagisa though, it was behind the shed. And he wasn't alone; he was talking to Terasaka, saying someone about how he should tell them the plan if he wanted the class to back him up. Naturally, he was rudely brushed off as Terasaka stalked off. Something about Terasaka's parting words stuck in Killua's subconscious. It was at times like this when Killua detested his gut; the feeling of not _quite_ being able to place what was wrong was aggravating. But it had saved him plenty of times, hence Killua always listened to his intuition.

When Killua approached Nagisa, he made sure to step a bit louder so as not to startle the other boy. It wasn't at a level a normal person would usually be able to hear if they weren't paying attention, but Nagisa still seemed to hear him coming despite being clearly deep in thought about Terasaka's parting words, something which Killua noted down.

"Oh, hey Killua."

"Hey. Can we talk?"

Nagisa blinked in surprise but agreed, since the more he talked with Killua, the more information about the other boy he'd be able to gather. He wasn't really sure why he was gathering information, but he figured that it was probably a combination of his upbringing (not that he'd ever mention it) and a habit that he'd cultivated for the purpose of this assassination his class was tasked with.

The two walked out into the woods, which was what clued Nagisa in to the fact that this conversation had to be very private if the already secluded area behind the shed wasn't good enough. That or Killua was taking him out into the middle of the woods to make it easier to dispose of his body? Well, he figured the first conclusion was more likely, though his mind's wanderings had managed to put himself on edge enough to note the path they were taking.

The two finally stopped at a secluded grove, which Nagisa had to admit was great for a private conversation, or even just to hang out (or a murder, whispered his subconscious- he strangled that voice).

"So, what did you want to talk about?"

Killua blinked, noting that Nagisa was a bit on edge. He wondered why until it occurred to him that this scenario seemed a lot like a mass murderer taking his victim out into the middle of the woods for ease of body disposal... He mentally facepalmed. Even when he wasn't trying to, it seemed like he was going to be stuck as a 'killer', huh?

This thought put him in a bad mood, so his reply was a bit aloof, "Was there a reason why you didn't want me accompanying you home?"

Nagisa was surprised. _'That's still on his mind?'_

Still, the question Killua gave managed to mostly assuage his doubts, and he answered, "Oh, uh, my mom... doesn't really like when I bring guy friends back home. She's really overprotective so... yeah. I guess she thinks they'll lead me astray or something?"

Killua noted the deliberate obfuscation, but didn't raise it. This wasn't what he called Nagisa out here for anyway (that, and he could always find out on his own, no, it's not stalking, it's _concern for a friend_ dammit).

"Ah. I wonder what she'll think if she knew you had to kill an octopus?"

Nagisa was silent. _'Is he threatening to tell my mom? Surely the government would stop him right???'_

"Uh, probably freak out actually."

"Then what do _you_ think about killing the octopus? I did raise the point before, but didn't get around to asking you or Karma about your thoughts. Sorry about rambling on back then."

Nagisa blinked, a bit off-kilter by the turn the conversation took.

"Oh, uh... I'm kinda glad you didn't ask us then, since we probably wouldn't have had a very thought out answer. But I have been thinking about it. Honestly... I'm still not really sure about the implications of killing someone. Sure, logically speaking, I know I'll probably feel guilty afterwards, but I can't know for sure until I actually do it... But then I think about how if I _don't_ , then the world could possibly end. Yeah, the government probably has their own plans, and we probably aren't even Plan A, but... what if we _could_ do something but didn't? I think I'd regret it. So, I'm on board with this assassination."

Towards the end, resolve had entered Nagisa's eyes. Killua cocked his head to the side slightly. "Huh. So do you like Karasuma's training sessions?"

Yet another curveball question threw Nagisa off from thinking about the intentions behind Killua's questions. This time, he took a while to think, during which Killua waited quite patiently. Finally, he spoke, "I... I know I'm not the best at using a knife or a gun, but... Karasuma-sensei is the best teacher I've ever had. So even though I'm not very good, it's still fun."

Killua seemed to consider his answer for a moment, as if sifting through his words to get to the conclusion he wanted. Finally, he nodded. "Got it. Well, that's all I had to ask, so I guess I'll see you tomorrow."

Saying this, he turned around and gave Nagisa a wave goodbye without even a backwards look, leaving a very confused Nagisa stranded in the middle of the woods. Well... it was a good thing he'd paid attention to the path they took, huh?

* * *

Even by the time Tuesday rolled around, Nagisa still hadn't managed to decipher the reasoning behind Killua's questions. He had covered a wide scope with his questions, which was honestly probably what the other boy had intended. Nagisa tentatively concluded that misdirecting was sort of second nature for Killua. Which honestly sounded more sinister than he intended to make it sound, but he didn't know how to word it better.

Killua seemed normal throughout lessons today, from what Nagisa had observed of him, so it probably wasn't something vitally important to him. _'He could have just been curious? But then why drag me out into the woods just for that?'_

When the class was dragged into helping Terasaka with his supposed assassination plan, he noted that though Killua wasn't actively participating, he still followed the class, seemingly curious as to what was going on. When everyone piled into the pool though, he hung back in the shade with Karma, the two of them being the only ones who managed to not be dragged in. Killua tried to get Nagisa to stay with them, but Nagisa felt like he should help the class with whatever it was, and so got into the pool too.

When Terasaka pulled out a gun, Killua raised a brow. Though, come to think of it, that gun looked a bit different from the ones handed out to the rest of the class...

In the split second before Terasaka pulled the trigger, Killua's instincts screamed at him to get the students out of the water. Not bothering to waste time thinking about why, Killua pulled out his yo-yos and shot them towards Nagisa's direction, managing to get a hold of around five of the students before an explosion rung out and the dam burst, causing the remaining students to be swept away by the current.

Cursing, Killua yanked the five students out (one of whom was a sopping, stunned Nagisa), and had taken off like a bullet out of a gun before Karma had even had time to process what had happened.

Through the combined efforts of Killua and Korosensei, most of the students were fished out of the water before they reached the cliff. Unfortunately, Hara was the one they couldn't get to in time, and she clung desperately to a branch sticking out of the cliff face. Due to the awkward angle however, Killua was unable to directly yank her up, for fear of causing her head to hit the cliffside. Just as he was looking for a decent branch to act as leverage to change the angle of his yo-yo, a white tentacle popped out of nowhere, smacking Korosensei, who had just been about to save Hara.

Killua's guard went up, as he surveyed the new arrival. No, the new _arrivals_. There was a man all covered in white cloth hanging a bit back from the boy who had... were those tentacles? Coming out of his head?

Now Killua was really stuck. If he tried to find a place to use as leverage for changing the angle of his yo-yos, they would definitely slow down enough to be smacked off course by the tentacle kid (he estimated the speed displayed to be roughly equivalent to that of his teacher's, which was an insane speed he might not be able to reach even with Godspeed), and might even put Hara in danger. But if he just threw the yo-yos out, he risked causing Hara to hit her head on the cliffside.

But just as he was considering his next move, Karma came in clutch with the plan to have Terasaka act as a distraction long enough for Korosensei to save Hara. Killua tilted his head, wondering how Karma knew Terasaka hadn't changed his shirt from yesterday. Did he have a nose as sharp as Gon's? No, probably not. He was pretty sure even Illumi's sense of smell wasn't as strong as Gon's. Well, except maybe if it came to blood... But he was getting off track. While he had been distracted, Korosensei managed to bring Hara to safety.

When the rest of the class (save for Karma), jumped in to pelt the tentacle kid with water, Killua hung back, warily observing the cloth-covered person who seemed to be the tentacle kid's handler. It was next to impossible to tell what they were thinking (considering they were all covered up), and the fact that they _were_ covered up in the first place suggested that they were either an eccentric (something he wasn't ruling out) or they were trying to hide their identity. It was the latter possibility that caught his interest, for it implied that they would be _recognised_ by someone in the class. The most obvious choice of course, would be their teacher.

So caught up was he in his thoughts that he hadn't really paid attention to tentacle kid and his handler being scared off, only coming back to himself when he saw the rest of the class approaching him. He was a bit puzzled as to what they wanted, but that was soon clarified by their shouts of "Thanks, man!", "You really saved us back there!", and "Damn I didn't know you could do that with a yo-yo!".

It took a while for it to sink in that they were thanking him for saving them, but when it did, a slight flush rose in his ears, which he tried desperately to hide. Unfortunately for him, Karma, Rio, and Nagisa had noticed. The former two because they had a sixth sense for the embarassment of other people and the latter because, well, it's Nagisa. Twin devil smirks appeared on Karma and Rio's faces, this being the first time they had sensed any form of weakness from their new classmate. Just as they were prepared to pounce though, someone else interrupted, saving Killua.

"I didn't know yo-yos could lift so much, damn! You grabbed like what, five people the first time?"

Killua had managed to bring himself back under control, as he reverted to his normal cool demeanour. He pulled out a yo-yo and showed the string to them. Some of the more eagle-eyed ones noted that it was made of metal and exclaimed in confusion as to why one would even _want_ a metal string on a yo-yo. This sparked a discussion of whether the metal was for aesthetic and just so happened to serve the function of allowing Killua to lift so much weight using just his yo-yos or was _actually_ for the sake of lifting weights. Naturally, most people fell into the former camp. However, Karma, knowing how much those yo-yos weighed, knew better. He had a feeling Nagisa had an inkling about the truth too, from the way he stared too long at the yo-yos.

Korosensei watched as his newest student was surrounded by his peers, seemingly getting along with them much more after he had just saved them. Korosensei had been worried that Killua would be isolated because of his refusal to partake in the assassination. Sure, he had noticed that Karma and Nagisa hung out with Killua fairly often, but he had been afraid the rest of the class wouldn't be as accepting of Killua. Now, he could put those fears to rest.

At some point, Yoshida had broken off from the crowd and was running from an enraged Hara. It seemed like he had made a remark about how he doubted Killua's yo-yos would've been able to lift Hara, and hadn't been able to listen to Killua's analysis as to why he hadn't been able to save her before Hara's murderous aura had him bolting.

It was at this point that Korosensei inserted himself into the gaggle of students and asked for praise too for saving them with his usual theatrical antics. He was met with a few scattered words of thanks, but mostly anti-sensei knives.

**Notes for the Chapter:**

> Next chapter is final exams time. I'm squishing chapters 15 & 16 together, since I don't have to devote content to the individual 'monster' questions.


	7. End-of-term Exams

**Summary for the Chapter:**

> Killua/studying? More likely than you think.

**Notes for the Chapter:**

> Look Asano, I’m sorry in advance, but honestly what’s the difference between losing in canon and losing a bit more thoroughly in this AU? Also, chocolate will be your downfall.

About a week had passed since the "Pool Incident", end-of-term exams were starting to sneak up on the students of class 3-E. During this time, Killua had mainly hung out with Karma and Nagisa, and so he had front row seats to their awkward dynamic. Sure, if it was a class activity, they were perfectly fine. But they didn't seem to know how to interact with each other outside of class, which was odd, given that he learned they shared similar interests in some comic series or something.

The others had warmed up to him too, and though they didn't invite him out as often as Karma or Nagisa, he still managed to get to know some of them a bit more. Killua didn't think he was going to get used to having this many people he could call friends any time soon.

Today, it seemed like their teacher had taken them outdoors to give a... pep talk? For finals? Well, that and apparently give the rest of the class an incentive to do well by letting the top scorer for each subject destroy a tentacle, which would apparently slow him down. Killua wasn't really interested, since he'd have to outright attack their teacher to destroy a tentacle. He had said he wasn't going to do that, and hadn't been given any real reason to go against his prior words.

Nagisa, who had taken to observing Killua whenever anything assassination-related was mentioned, noticed his disinterested expression. He chewed his lip and worried at it while contemplating the reason. It didn't take him long to come to the conclusion that Killua might not want to do his best just so he didn't have to choose between going against his previous words and upsetting the rest of the class by outright refusing.

Suddenly, an idea came to him.

* * *

After classes, when almost everyone had left (Killua was hanging out with Karma today, so he had left already), Nagisa approached their teacher.

"Yes, Nagisa-kun? Was there something you needed?"

"Yeah. I'm worried that Killua-kun won't want to do his best just so he won't have to attack you."

Korosensei rubbed his chin. "Yes, that does seem in character for him."

"So, I was wondering if he could let someone else destroy a tentacle in his stead if he does manage to take a top spot?"

Korosensei's face was as inscrutable as always, with the constant grin plastered on. Finally, after Nagisa had started doubting himself and wondering if this was a good idea, Korosensei replied, "Well, I suppose I never said the top scorer couldn't let someone else take over instead."

Nagisa's face lit up.

"Though I doubt just this alone will be enough to motivate Killua-kun."

Nagisa merely smiled, and said, "I actually have an idea for that."

"Nurfufu~ Is it what I think it is?"

"You'll just have to wait and see, sensei."

"I look forward to it." Saying this, green stripes appeared on Korosensei's face.

* * *

Well, to be frank, it couldn't really be considered sensitive information, so it would've been fine to tell his teacher... except he had to ask Karasuma-sensei first.

Said (ex?)military teacher currently had a pondering look on his face. It finally looked like he made up his mind. "Very well. I will request it from the higher-ups. No promises, but I think it has a high chance of being approved."

Saying this, Karasuma looked like he had an almost smile on his face, which was honestly the best Nagisa had hoped for since he didn't think he had ever seen this teacher of his actually smile.

"Thank you, Karasuma-sensei."

* * *

The next day, Karasuma pulled Nagisa aside during lunch break and told him that his request had been approved. Nagisa lit up, thanked Karasuma, and went to go find Killua.

He found the other boy hanging out on a tree, for once not eating chocolate, which was a such a rare sight Nagisa couldn't help but stare. Noticing his gaze, Killua met his eyes and raised a brow as if to ask why he was staring.

"Oh, uh, I was looking for you."

Killua finished up his lunch, put the container in his bag, and leapt down from the branch he was sitting on. "What for?"

"Well, uh, I know you don't want to attack Korosensei directly so, uh, I asked Korosensei if you could hand over your 'prize' to be claimed by someone else and he agreed."

Killua blinked. At first, he was a bit surprised that someone would go out of their way to do that on his behalf, but upon remembering the prize in question, felt like he should've expected it. But before he could make a reply, Nagisa continued, "And I asked Karasuma-sensei if we could get funding for chocolate as a prize for yourself if you did get a top spot."

At this, Killua's eyes lit up. He knew he was being manipulated, but dammit, it was chocolate! Still, he had to play it cool...

"How much chocolate are we talking about?" Or not. _'Curse you traitor mouth.'_

* * *

Let's just say the amount of chocolate he was promised was enough for Killua to decide to actually commit to studying, which is no mean feat.

It was this reason that had Killua accompanying Nagisa's study group to the main campus, which he usually would've avoided like the plague, even during assemblies. Hey, if Karma can skip them, Killua could too. It wasn't like he was going to be expelled, though even if he was, he couldn't give less of a shit.

He mostly came along to see how normal people studied; the 'studying' method his parents put him through during his early training would probably scare off his classmates if they happened to stumble upon him, so he figured it was better to observe them and see how best to blend in. However, when a bunch of A Class clowns came by and tried to take their seats, he was beginning to doubt that appearing normal was worth all the effort.

Fortunately, since there were more members of the study group than those A Class bozos, by some stroke of luck, none of them decided to invade his personal space like they did the others. Still, it was making him uncomfortable enough to be tempted to act...

But before he could do so, his classmates drew various pieces of stationery and pointed them threateningly at the monkeys' vital spots, which scared them off enough to go running with their tails between their legs- though they _did_ leave an ultimatum behind before doing so. He blinked, before whistling lowly (remembering he was in a library).

The rest of the study group, save for Nagisa, had never gotten anything close to a compliment from Killua, so they were a bit surprised (but happy) to hear that whistle. 

Luckily for them, the rest of the study session goes uninterrupted, the rest of the students no longer daring to harass them now that even their top students had been scared off.

* * *

Karma was surprised to find that Killua was actually studying, as the other boy had never shown any academic inclination before now, and much like himself, was just naturally good, which was probably partially why the two had hit it off actually.

"Hey, thought you weren't going to attack sensei?"

"Yeah, I'm not. If I get a top spot, I'm letting someone else do it for me."

Karma blinked.

"Plus I'm being paid with chocolate."

Ah. Yeah, that would do it. Though it had to be a ridiculous amount of chocolate to get Killua of all people to voluntarily study. Karma figured that if Killua's academic abilities were anywhere near to his physical abilities... well, then it looked like he'd have to at least skim the material a bit more if he wanted to beat the other boy.

* * *

When the end of term exams finally came, everyone was overcome with nerves. Even Killua was a bit on edge, though that was less due to the pressure of the upcoming exams, and more of not knowing what kind of environment they were going to put through during the exams. Killua had gone through plenty of exams in the past before, granted not all of them were written, but given his previous and current occupations (assassin and Hunter respectively), he'd never exactly had the opportunity to experience a normal exam in a normal(ish?) school.

The examination room was pretty cold, but Killua figured he'd treat it like one of those locked freezer puzzles his family put him through (people get locked in cold rooms more often than they'd think, especially when they had to do stakeouts...). He doubted he'd be able to leave early though, which was a fact confirmed by the proctor not a few seconds after they entered. And was it just him, or was that proctor sneering at them? Was that allowed?

When the exam started though, Killua immediately got to work. The power of (promised) chocolate spurred on his fighting spirit.

* * *

_'Man, those questions were tough.'_

Killua stretched, having just got out from the room where the final subject's examination had taken place. _'Considering I was at the level of the equivalent of a student who just entered college in this world... This whole school's nuts. Glad I studied; I was pretty rusty.'_

After exams ended, there was the usual clumping up of students comparing answers, which Killua deftly navigated through as he made his way outside. There weren't any more lessons held on the same day as the exams; their next class would be tomorrow, though it would be more of a revision of what they learned.

_'Well, I've been putting it off long enough to study. Guess I should get started with preparations.'_

* * *

It took about a week and a half for the exam results to come in, which was already pretty damn quick considering the teacher to student ratio. And it wasn't as if the fastest teacher was allowed to help with the marking process since a) he was a national secret, and b) he taught E Class. A moment of silence for the poor educators of this fine facility, who are probably halfway in their graves from the stress of marking all those papers with such a tight deadline.

Anyway, back to the results. When the first top scorer was announced, the whole class nearly burst into cheers, but restrained themselves so as to know the results for the rest of the subjects. Almost every subject had the expected top scorer, with the exception being Literature, where their top scorer did slightly worse than Asano. When it came to Math however, they were all surprised to find that Killua had managed to snag the top position. Or, well, force Asano to share it anyway. They had expected Karma to be the one to claim top in Math for their class, given that he had claimed it the last time, but come to think of it, they hadn't heard Karma's name in any of the top spots...

Killua didn't think so much. He was just glad he got a top score; that meant he was getting his chocolate. He'd scored third in science, but the rest of his subjects were in the middling average of the entire E Class. Taking exams in a new language was hard...

* * *

The class got a surprising 8 tentacles down, 4 out of the 5 core subject's top scores claimed (though Killua had to share his spot with Asano), and a surprising last minute reveal by Terasaka's group that all four of them had tied for first place in Home Economics. Korosensei was visibly sweating at this point, but Karma wasn't in the mood to poke fun at him- not when his results were so subpar compared to his usual scores.

Killua was a bit surprised to see the redhead stalking off, and was about to go up to him to ask what was wrong, but his gut told him the other needed some space, so he listened to it. At this point, Nagisa came up to him, taking his mind off Karma's odd behaviour. "Congratulations on getting a top spot, Killua-kun! Have you decided who you're going to ask to destroy a tentacle on your behalf?"

"Yeah, you'll do."

Nagisa blinked, and pointed at himself questioningly. "Me? Why me?"

"Dude, you're literally the one who arranged things just so I'd be motivated. Who else would I pick?"

"O-oh, I thought you'd pick someone better, like Karma-kun."

Killua shot him a side glance. "We're working on your confidence."

Saying this, he walked off, leaving a very confused Nagisa behind in his wake.

**Notes for the Chapter:**

> Look if they can somehow get funding for a giant pudding, they can get funding to motivate a chocolate addict, okay?
> 
> Also, I grew up in an Asian country, but it's not Japan, so there's probably some differences in the education system, but I'm using my own exam experiences. I have had to take exams in a new language too, since it was a compulsory subject, and not even one where the language itself was taught, more like "ethics" but in a different language. Kinda regret coming to a different country to study because it's cheaper... Thought all the classes would be in English, but given I have citizenship here, guess they assumed I was given the basic education? Haha.


	8. Training

**Summary for the Chapter:**

> For whom? Whomst? Gah, English.

**Notes for the Chapter:**

> All jokes aside though, English is my native language. It's just a bit... wonky after picking up Chinese and going through a translation phase.
> 
> Comments really fuel my motivation. Last chapter had a comment that kicked my muse into gear so this chapter came out faster.

Killua had asked Nagisa to meet up with him the weekend after finals had ended. Killua made sure to tell Nagisa before their summer vacation officially started as he didn't want to reveal that he knew where Nagisa lived by going straight to his house.

Nagisa was a bit curious as to what Killua wanted, and would've assumed it was just to hang out, but Killua had said to meet up on the E Class mountain instead of somewhere off campus.

* * *

After a day of hanging out with Sugino and his friends on the mountain, Nagisa's mind naturally drifted towards assuming Killua had something similar in mind, though he doubted the other kid was a fan of bugs.

As a result, he naturally dressed for the purpose of hiking through the wilderness (thank goodness his mom hadn't been home). Even if Killua wasn't planning to, it didn't hurt to be prepared.

On the day they had planned to meet up, Killua was waiting for him at the foot of the mountain. Nagisa jogged up to him, waving a hand in greeting, which Killua returned with a simple nod. "Follow me."

Saying this, he started marching into the woods. Nagisa was glad he had come prepared.

Killua led him to a different part of the mountain than last time (at least, Nagisa thought it was, since previously they had travelled from the top downwards while this time they were travelling up the mountain). There was a similar clearing as the last time, but what proved it was a different one was the small creek running through the side. Well, that wasn't the first thing he noticed though. What he first saw was a clearing with various bits of wood, stone, gravel, tiles, and even the occasional cans and candy wrappers strewn about haphazardly, as if someone was using this as a dumping site.

Nagisa was a bit confused as to what they were doing here.

At this point, Killua turned around, his hands still in his pockets. "We're here."

"Where is here exactly? And what are we doing?"

"For the first question, doesn't matter. For the next, I'm getting to that."

Saying this Killua walked across a small section of the debris and turned around to Nagisa. "Well? Notice anything?"

At first, Nagisa didn't get what Killua was talking about. The white-haired boy rolled his eyes and continued pacing back and forth on the debris. Nagisa's confusion only grew, along with a niggling feeling at the back of his mind. It was when Killua stepped into the stream, completely silently, that a lightbulb lit up in Nagisa's brain. Killua's footsteps had been completely silent, to the point that if Nagisa hadn't been looking, he wouldn't have even known someone was walking. He had grown so used to his classmate's low presence and near-silent approaches (thanks to Killua being considerate enough to warn others he was approaching), that it had taken a while to catch on. Noticing Nagisa seemed to have got the hint, Killua walked back.

"That's amazing, Killua-kun! It would be so useful for assassinat-" Cutting himself off from saying something that might upset Killua, Nagisa shot a careful glance over at Killua to see if he noticed his slip up. If he did, Killua didn't seem bothered, or at least didn't display any signs of being upset.

"You're already pretty decent at approaching undetected- which, by the way, has me a bit worried for your home life," to which Nagisa tried to deny it, but Killua didn't give him the chance to say anything, "but that can wait for some other time- What I'm trying to say is, that though you're already good at being stealthy, it's not quite at the level of being able to sneak past a pro, let alone the guy you're trying to assassinate given his senses."

Nagisa felt rather dejected, knowing it was the truth. It was this that caused him to not register the fact that Killua had said this with the confidence of someone who knew the abilities of a pro...

"Try walking over this bit here." Killua pointed with his chin, using his foot to further indicate where he wanted Nagisa to walk. "And try your best to be silent."

Nagisa did as instructed, but the area Killua had told him to walk on was a plank of wood that was placed over several stones, causing it to be a bit uneven. This resulted in Nagisa being unable to accurately judge where to apply pressure correctly, causing the plank to tilt and creak, ruining his stealth attempt. Killua had made it look so easy to be able to walk over all this completely silently, but now that Nagisa was actually giving it a try, he was finding it much harder than expected.

"You noticed? When stepping from one surface to another, or on something placed precariously, tends to be when people make the most noise even when trying to be stealthy. This is because their brains haven't gotten used to how much pressure to apply and where would be best for reducing noise."

Nagisa looked at him, his interest having clearly been caught, but still wondering why Killua was saying all this. It couldn't possibly be because...

Killua met his eyes. "That's why, you're going to be practicing here until you can run silently. Bonus points if you can enter the creek silently, but I won't make you run for that. Bit hard to fit that in the timeframe we have."

Nagisa almost couldn't believe his ears, staring at Killua with barely concealed disbelief, which the other boy naturally caught. He gave an impatient huff, "What? You got a problem?"

"N-no, it's just... Are you, er, training me?" Towards the end, his voice petered off, as if afraid he had offended Killua.

Killua cocked his head and raised a brow. "Was I not being clear enough? No shit I'm training you."

Nagisa was so stunned he didn't respond for a good few seconds.

"Hello? Earth to Nagisa? If you're not interested, we can just forget about it." Saying this, Killua, turned as if to leave, to which Nagisa almost shouted, "No, wait! It's not that I'm not interested. I was just... surprised."

Killua turned back around and cocked a brow, as if to ask him to elaborate.

"It's just... I thought you wouldn't want anything to do with the assassination, so the fact that you're training me for it... kinda caught me off guard."

"Yeah, well, I felt like it. Now anymore questions before we start?"

Nagisa fell silent before speaking, "Why me?"

"Why you what?"

"Why pick me to train? I-it's not that I'm not grateful, but surely others in the class would be better...? Even if you didn't feel comfortable enough with them to train them, why not Karma-kun? You guys seem to get along pretty well."

Killua shrugged. "You've got the best foundation for this- I'm not talking about using weaponry, I'm talking about stealth and footwork. Plus you've got an extra edge Karma doesn't have."

Nagisa didn't feel convinced about that last part. He also felt like Killua was still hiding something from him, but honestly? The fact that he was willing to train him at all made Nagisa willing to ignore that.

* * *

The two trained for the rest of the day (well, _Nagisa_ trained, Killua just supervised and corrected him), and by the time the sun was starting to set, Nagisa was both mentally and physically exhausted.

Deciding to end off for the day as it was getting late, Killua stopped Nagisa, who was almost tempted to keep going until he got the hang of it. "Good job. You made pretty good progress today."

Nagisa must've let the doubt show on his face, for Killua elaborated, "I wasn't expecting instant results. Sure, you've got the foundation, but you've never really trained, self-trained or otherwise, so I'm not surprised. You still have the rest of the week."

Nagisa looked a bit down, so after a bit of pondering Killua spoke again, "Look, if you can do this by the end of the week, I'll teach you something more advanced. Guarantee it'll at least catch your target off guard."

Nagisa looked a bit curious as to what Killua was talking about, but the other boy seemed determined to keep it a mystery for now.

* * *

As the days went by, slowly, Nagisa got the hang of subconsciously adjusting his steps to match the terrain. He still couldn't really enter the creek silently, but he wasn't too bummed by it, already being too excited with the rest of his progress. Killua had been a surprisingly patient trainer throughout, giving him the occasional hint (though mostly letting him figure it out on his own), as well as giving him suggestions for his body posture that would make adjusting his footwork easier.

Killua had made sure Nagisa didn't stick to just one area or particular type of terrain, occasionally even changing things up before Nagisa even got here, just to make sure he was learning the skill and not just memorising the layout.

On the fifth day, Nagisa was already able to take slow walks silently through the training grounds, to which Killua had given him an approving nod. Honestly? At this point, Nagisa didn't really care about the advanced skill Killua was offering to teach; Killua was a good enough teacher that he was enjoying himself regardless, the possible new ability was just a bonus that he wasn't really expecting to get. It was because he was lost in his thoughts that he hadn't noticed Killua suddenly changed his posture, so the sudden impact to his back caught him by surprise.

Whirling around, Nagisa noticed an anti-sensei knife that had fallen to the ground, having just been launched at his back.

"You're not paying enough attention to your surroundings. Though I wanted you to work on your footwork and stealth, it has to be on instinct so you can always pay attention to your surroundings." Killua spoke sternly.

Nagisa looked at him, almost betrayed.

"Don't look at me like that, you're lucky I didn't decide to have you run the course while dodging attacks."

Nagisa shivered at the thought.

"I almost did, but didn't due to time constraints."

Nagisa thanked every deity out there for this stroke of luck, since he had the feeling his classmate had a sadistic streak that could rival Karma's; it was just kept very well in check most of the time.

Meanwhile, Killua was very resolutely ignoring the distant gaze he could feel on the back of his neck. He had a feeling he knew who it was, but he didn't particularly care if this extracurricular activity was discovered, as long as he wasn't harassed or pressured into training others. In the distance, Korosensei rubbed his chin thoughtfully. He had spotted the two meeting up and heading into the mountain the past few days, which had caught his attention. He never would've expected Killua to take the initiative to train Nagisa, but now a few more puzzle pieces slotted themselves into place, almost allowing him to view the full picture of the enigma that was Killua. "Nurfufu~ How interesting."

* * *

By the last day before the deadline Killua set was up, Nagisa was able to do short sprints silently over the terrain, though longer ones were still beyond him. He could also enter the creek silently half the time he tried now. He wished he had more time to practice; he had the feeling the key was in the timing.

As the sun started to set, Killua called a halt. Nagisa was a bit disappointed that the training would be over now. Sure, he _hoped_ Killua planned to train him further, but he wouldn't pressure him to.

"Not bad. You've got the basics down. Now a _certain octopus_ can stop watching us like a creep!" Towards the end, Killua raised his voice and turned in the direction the stare that had been pinned to him the past few days was originating from. Sure, he hadn't minded at first, but given his former profession... well, long periods of being stared at tended to raise his hackles, y'know?

Nagisa blinked and looked in the direction he was looking at, only for a yellow blur to appear in front of them, to reveal their teacher. "My, my, Killua-kun, I didn't expect you to notice me."

Killua remarked drily, "It was kind of hard to ignore you with the constant staring."

Nagisa hadn't noticed Korosensei's presence at all; he had been too far away, and Nagisa had assumed his eye-catching colouration would've given him away. Evidently, that wasn't the case. He wasn't really surprised that Killua had noticed him though; he'd kinda just accepted that Killua had skills beyond his (and most normal humans) at this point.

"Korosensei, why were you watching us?"

"Well, I was a bit worried that two of my students were going into the mountains alone without adult supervision, so naturally, being the amazing teacher that I am, I had to keep an eye on you two."

Nagisa was a bit worried at first that Korosensei knew how he was training, but on further contemplation, concluded that it didn't really matter, since Korosensei wouldn't know when he'd use this new skill, so he'd still retain some element of surprise...

"Now that we're done, you can go bother your other students." Killua remarked bluntly.

"As blunt as always, Killua-kun. Oh, when will I melt your icy heart?" Saying this, he threw up a hankerchief in a dramatic pose. Nagisa, naturally, threw an anti-sensei knife at him, causing him to zoom off, to which Killua looked at him appreciatively.

"Well, now that we don't have any other prying eyes and ears around, let me finish what I was saying: congratulations, you've gotten the basics of Shadow Step."

Nagisa blinked. This skill had a name? He didn't really expect that...

"I guess I can teach you Rhythm Echo now."

Nagisa remembered that Killua had promised to teach him a more advanced skill if he successfully ran through the terrain, but he had thought the short dash he could manage wouldn't have counted.

"Though I'm not holding out much hope you'll be able to learn it. Who knows?"

Before Nagisa could think of a reply, Killua started walking sideways, whereupon something strange happened: it was as if the edges of his form blurred and formed countless afterimages, that looked almost like Korosensei's afterimages, but Killua wasn't moving nearly as fast as Korosensei!

Nagisa felt like his mouth was agape, but couldn't spare the mental capacity to shut it, too absorbed in watching Killua forming afterimages by just pacing. Finally, the white-haired boy came to a halt, but where his form solidified wasn't where Nagisa had expected him to be from following the afterimages. His mind immediately made the connection that this skill would be exceptionally useful for assassination, a small part of it wondering why and how Killua had learned this skill in the first place.

"I'm not going to ask you if you learned anything from that. I doubt your senses are sharp enough to catch it, but what I did was change the cadence of my footsteps to a certain rhythm, allowing me to produce 'echoes' of myself. Hence the name, Rhythm Echo."

Nagisa tried to recall if he had noticed anything, but like Killua had said, he hadn't really noticed, having been too distracted by the multiple afterimages to watch his feet.

"We can continue this tomorrow; it's getting late."

Only now did Nagisa notice the sun was nearly down, causing the ground to be shrouded in darkness.

Killua walked him down the mountain today, and tried to walk him home, but Nagisa had enough presence of mind this time to tell him he could go home on his own after descending the mountain. Like before, Killua agreed, but this time, he spoke quietly before leaving, "You know, you can talk to me about your home life if you need someone to unload on. Promise I'll keep my mouth shut."

Nagisa was a bit surprised at the olive branch extended to him. That was... surprisingly tactful of Killua. He couldn't help but feel his heart warm to have such a good friend.

**Notes for the Chapter:**

> So I'd like to know how many people guessed that Killua's plan was to train Nagisa? I think I left a pretty big hint when I said he got the idea after the training session where he was paired up with Nagisa. I pulled all this out of nowhere by the way, so really it's just what I think would help with footwork and stealth, but given I'm not the athletic type (haha, 100 meters feels like 100 kilometers), I am not claiming accuracy at all.


	9. Lovro

**Summary for the Chapter:**

> Pro-assassin meets ex pro-assassin. Not that he knew it.

**Notes for the Chapter:**

> Many, many different scenarios ran in my mind for this chapter, but most of them had a few out of character moments that caused them to be unfortunately scrapped, as awesome as they were, which is a shame. I hope the one I settled on is still good. Words words words, why have you forsaken me?

Nagisa was training with Killua again today. They were going on their second day of working on Rhythm Echo, with no results to show for it. At least he could run further using Shadow Step now though, which was an improvement that Killua had remarked upon. Speaking of the white-haired boy, Nagisa's mind couldn't help but relive him using Rhythm Echo. The way his form blurred as it split apart into multiple afterimages, the seemingly casual way he seemed to pace. All of it caused doubt to sprout in Nagisa's heart about whether he'd ever be able to pull off even an inferior version.

Noticing Nagisa was lost in his thoughts ( _again!_ ), Killua threw another anti-sensei knife at him, though this time Nagisa was paying more attention to his surroundings (well, mostly Killua) and so managed to dodge it by a sliver of a hair. Killua gave him an approving nod. Though he hadn't launched that knife with any actual strength, since it was mostly meant as a way to bring the blue-haired boy back to earth from wherever his thoughts had sailed off to, he knew that few others in the class would've been able to dodge that throw, even if they _had_ seen it coming. Karma probably would've been able to dodge it, but Killua wasn't sure any of the rest had the same instincts. Sure, some were objectively better at sparring with the anti-sensei knives, but it was just sparring, so it wasn't like he had a chance to see any of them in any real action.

Though maybe Isogai? Weren't some people mentioning some baseball match before where he was picked for... something? Because of his fast reaction speed? Killua didn't really follow sports, so he didn't even know if this world's sports had different rules from his (not that he even knew the rules to those). The closest experience he had to sports in any form was... way back when he was on a mission, and some kids happened to kick a ball his way. He stopped that train of thought before it got to what happened to those kids (Illumi was around).

Shaking his head, Killua turned his full attention back to Nagisa, who was still trying to reproduce the cadence of steps used in Rhythm Echo, to no avail.

* * *

When they stopped for a break, Killua approached Nagisa. "So what were you thinking so deeply about?"

Nagisa rubbed the back of his head. "Well, it's just, you're going to all this effort to help me and I don't even know if I'm going to succeed in learning the skill you taught."

"Okay, first of all, I'm not 'going to all this effort'. I'm just doing what I feel like, got it? You're the one actually training, I'm just standing on the sidelines watching. Second of all, I believe I've said it before, but I'll repeat myself in case you forgot: I'm not expecting you to _have_ to learn this skill. In fact, I'm not holding out much hope at all since you've only just barely got the foundation. That's why, regardless of whether you succeed in learning Rhythm Echo, I'll still be training you, understood?"

Nagisa wasn't really sure how he felt about Killua all but saying he didn't believe in him, but considering the other boy was still training him... it didn't feel like Killua was _actually_ saying he had no faith in Nagisa, more like he was saying it to reassure Nagisa. He felt like he preferred this to the constant pressure he face back home. He liked it.

* * *

"Oh yeah, I think the class mentioned they were going to meet a week before we go on the island trip to brush up on our training. It's... in three days actually. Are you going to join, Killua?"

Killua considered it for a moment. "Mm, sure I'll go. But I'm not training, I'll just go to watch your progress, see if you need any pointers or just more practice."

Nagisa felt pretty happy. Despite what Killua said, he was clearly going out of his way to help Nagisa, which the latter could tell, but wasn't going to reveal that he knew, since he was almost 100% sure that Killua would either divert the topic or deny it again. It seemed like he was getting a pretty good feel of Killua's personality.

* * *

The remaining few days passed by, still without any progress on Rhythm Echo by Nagisa. But on the bright side, he could now run through the clearing using Shadow Step, as well as enter the creek silently about 7 every 10 times now, which was a marked improvement that earned him some outright praise from Killua. Nagisa didn't really know what to do about being praised so often by someone who gave them out so sparingly. He guessed he was kinda similar in that way to Killua, who always seemed slightly caught off guard every time he was praised, it being more obvious if the praise was new (of course, this was only Nagisa's inference). If you praised Killua for his skill with a weapon, or sharp senses, he seemed to react as if it were a matter-of-fact, but if you praised him for doing something like save people or his leadership skills, he'd always appear vaguely surprised, as if he hadn't expected praise for those things.

Nagisa pondered this as he and Killua made their way to the E Class campus, luckily having made it an instinct for his feet to be able to step on any terrain stably by now, else he would've tripped over a root by this point. Still, it took Killua tapping his shoulder for him to realise they were almost at the campus. He was about to apologise when Killua spoke, "I'm not going out there. I'll stick by the trees so I don't get dragged into training."

Knowing he couldn't really convince Killua to do anything he didn't want to, Nagisa resignedly nodded.

As he watched Nagisa enter the training grounds and be greeted by their classmates, Killua allowed his gaze to travel over the others who were training. _'Could be better. Posture's not the most efficient, but it'll do. Should be using their back more. Eh? Those two look pretty good.'_

The ones he was talking about were Chiba and Hayami, who were currently coolly practicing their marksmanship. _'Ideal posture, good aim, solid breathing. Just wonder how they'll do on the field.'_

Just as he was contemplating whether he should go up to them and give them pointers or ask Nagisa to do so in his stead (he was leaning towards the latter), Killua spotted Karasuma approaching the training field. He was accompanied by a tall man with a dour countenance, that had features that seemed foreign to Japan. Killua raised his guard. He couldn't help it; he'd been conditioned to always have his guard up- it was already pretty decent progress that he'd learned to let it down around people he was close to.

He stared at the man. He knew he wasn't being subtle, and the man had probably caught on that someone was staring at him if he had any shred of competency whatsoever, but Killua knew that he was stronger than almost everyone in this world, so the only threat the man posed was to his classmates, and Killua would be damned if he let any hint of malice slip past because he was trying to be subtle.

He watched the man seemingly say something to that scantily clad old hag that caused her to startle and run back inside. He contemplated their interactions. It didn't seem as though she was _afraid_ of being harmed, more of... being told off? Killua nodded to himself, yeah that seemed to be the case. Since this old hag and Karasuma seemed okay with him, neither showing any signs of tension (well, not more than usual anyway), Killua decided that the newcomer could be classified as 'safe' until otherwise proven, and so shifted his gaze back to the students.

* * *

Lovro had felt a gaze land on him almost immediately when he came within sight of the training field. At first, he couldn't pinpoint it, but after a quick sweep over the students, realised that it wasn't any of them, and so discreetly attempted to find the source of the gaze out of the corner of his eyes. As a pro-assassin, he had to always be on alert for any signs of danger or a job going sour.

However, Karasuma spoke at this point, "Don't worry if you feel someone watching you. I would've bet it was the target, but we've got confirmation he's gone, so the next most likely person is one of the students. I have an idea of who it might be. If you find yourself interacting with him, try not to antagonise him- orders from higher up."

Lovro hid his surprise well, having decades of experience, but it wasn't often that he actually felt the feeling, so curiosity soon followed in its wake. What kind of student could warrant such an instruction?

Still, Lovro was a professional. He was brought here to train the students, so once he had established the watcher wasn't a threat (at least for now), he immediately got back to the task at hand.

Naturally, he noticed the same things Killua did, though he was more generous in his judgement for the students in general. Spotting Chiba and Hayami, he couldn't help but feel the urge to take them on as his personal students; they really were quite promising seedlings.

That was when a short, blue-haired boy approached him, getting his attention. The moment he focused on the kid, his eyes lit up (as much as his near constant sour expression would allow anyway). Whereas the others displayed varying levels of skill in weaponry, Lovro, with his many years of experience cultivating aspiring young assassins, could tell with a glance that this unassuming boy had the potential to be the most dangerous of the lot.

"Um, excuse me sir, but are you an assassin?"

Lovro hummed and nodded his head. "Why? Are you interested in the business of assassination?"

"O-oh, no, I was just curious to know what it's like to be a full-time assassin."

Lovro pondered for a bit. The kid was clearly interested in assassination, despite his denial. "Well, it's a bit tough to explain to someone outside of the business. How about I teach you a secret technique of mine instead so you can get a firsthand feel for it?"

The kid hesitated, seemingly not knowing what to do. His gaze appeared to subconsciously sweep the treeline, where Lovro had pinpointed the gaze from before to have originated from. Following the child's gaze, he finally spotted a white-haired boy in the branches. The boy seemed to meet Nagisa's gaze before hopping off his perch, dusting himself off, and ambling towards them.

Lovro noted that only those students who had been facing the general direction of the forest seemed to have noticed him, the rest appearing to be a bit confused before turning to look, and only then seeing the white-haired boy. To have such an eye-catching appearance and yet have such a low presence without looking like he was particularly trying to hide himself... Lovro felt like he ought to revise his prior evaluation that the blue-haired boy was the most talented of the bunch.

He watched as the boy returned his classmates' greetings with small nods or casual waves as he strolled over to stand beside Nagisa. He didn't seem to pay much mind to Lovro himself, instead focusing on Nagisa, his head cocked to the side in a silent query. However, Lovro, who was taking this chance to examine the mystery student up close, noted that though the boy's posture and demeanour appeared casual and dismissive on the surface, he was in actuality always poised to spring into action, reminding Lovro of himself and other veterans of his line of work. But that couldn't be, could it? He was too young...

As Lovro teetered on the brink of questioning everything he knew, Nagisa was busy sheepishly explaining to Killua the reason he had looked to him; Lovro wanted to teach him a new skill, but since Nagisa was training with Killua first, he figured he'd ask his opinion. With the wording Nagisa used, Lovro naturally assumed that Nagisa and Killua were training _together_ , he couldn't have guessed that Killua was training Nagisa.

It was at this point however, that the white-haired boy turned his gaze to Lovro. When Lovro's eyes met the boy's, he felt like he was being sucked into a void where thousands of invisible knives sliced at his very being until his core self was revealed. It wasn't until Killua looked away that Lovro realised he'd been holding his breath, a hair-raising feeling that he hadn't felt in a long, long time having crept up the back of his neck. Looking at the boy again, the feeling didn't appear again, which almost convinced Lovro he'd been hallucinating, had it not been for the fact that he realised only now that the boy's eyes were blue. Usually, that would've been something his subconscious would've registered when he first saw a new person, but the fact that he only now registered it implied that all of his attention had been solely focused on a threat.

Yes, a threat, that was the word. That hair-raising feeling was something he'd felt only once before, when he'd been much younger and inexperienced. It took a while to name it, but when Lovro did, he was almost surprised, and yet not, to find that it was akin to the feeling a prey animal had when they encountered their natural predator. Just who was this boy to inspire such fear in a pro-assassin with decades of experience under his belt who had trained countless others?

While Lovro was busy having his internal freakout, Killua had turned to Nagisa and said, "You can train with whoever you want, probably better to get a second opinion anyway, since I'm new at this and all."

Having said what he wanted, Killua turned and left before anyone had the bright idea of dragging him into training with them. He didn't mind the normal training sessions during PE; he just treated it as a lighter version of his normal workout. But wanting him to actually put effort into training with the others was something he wasn't interested in. None of them could really keep up with him like a certain green-haired boy had, so training with them didn't interest and excite him as much. Plus if he accidentally revealed more of his strength to them, they might start harassing him to help with the assassination again, and he was just starting to get used to having many friends, so he didn't want to lose them so soon.

Nagisa internally sweatdropped when Killua walked off just like that. He was kind of worried he'd offended the other boy; he could never really tell with Killua. Still, he had to turn back to address Lovro, "Sorry about that Lovro-san. Killua-kun can be a bit blunt at times."

However, Lovro didn't seem to really hear it, as he responded with a noncomittal hum.

* * *

Killua watched as Nagisa walked off into the woods with Lovro. He felt like the other guy was safe enough (plus he was pretty sure he'd given him a good enough scare to not go overboard), but he was a natural worrier. Just as he was contemplating ~~stalking~~ _keeping an eye on his friend_ , he was approached by Karma.

"Yo, you've been hanging out a lot with Nagisa-kun lately. Saw you guys at the foot of the mountain a couple of times. What were you guys up to?"

"Hm?" Killua hummed. "Oh, that. I was just having Nagisa train his footwork and stealth a bit more."

Karma blinked. "You were training him? You? Mr I-don't-want-any-part-of-this-assassination?"

He then jokingly lamented, "This is favouritism I tell you."

Killua gave him the side eye. "He’s pretty much the only one who I’ve got the confidence to train up to at least a basic level in such a short timeframe. For everyone else, it’s better if they focus on their own strengths."

Karma raised a brow before asking half-jokingly, half-seriously asking what it was Killua thought he should work on.

Killua hummed as he thought. Karma didn't rush him, simply allowing Killua time to think. Finally, Killua spoke, "You should work on improvised weaponry and psychological attacks, though I'd prefer if you didn't go overboard when practicing the latter on our classmates-" at this, it was as if devil horns and a tail appeared on Karma, "-since your nature lends itself to a more tricksy fighting style."

Karma complained, "Aw, c'mon, don't put it that way. I prefer the term 'playful'."

Though he said this, Karma wasn't being serious- on the contrary, he was quite happy that Killua had thought through his question before answering. Still, this didn't stop Karma from requesting, "Say, would you be my sparring partner then?"

Without even the slightest hesitation, Killua refused. He then elaborated, "Don't feel up to it. You should be working with many different partners anyway so you can work on how to deal with different opponents."

Karma attempted to bribe Killua with chocolates, but the other boy smugly informed him that the prize for the top spot he got was all the chocolate he could eat for a month.

"..."

* * *

The lesson with Lovro wasn't so much a lesson as it was a brief demonstration and explanation of the skill. Afterwards, Nagisa was pondering how he should go about practicing it (he doubted Killua would be willing to act as the guinea pig/target). Just as he was about to reach the training grounds, he spotted Killua hanging out on a branch. Killua turned to look at him, before hopping down from his perch and walking up to Nagisa.

"So, how'd it go?"

Nagisa was a bit surprised that Killua hadn't followed them, but he figured it was either because Killua didn't want to annoy a pro-assassin (in another universe, an author is cracking up), or because Killua wanted to respect his privacy, though both reasons seemed a bit flimsy. He gave an unsure hum as a reply to Killua's question.

Killua then asked if he was returning to train with the rest of the class, but Nagisa managed to surprise him by saying instead, "Can we walk instead? I kinda wanted to talk with you."

Killua was rather curious as to what Nagisa had to talk about, but he agreed without asking about it.

As the two made their way to the clearing they'd been training in the past few days, silence fell between the two of them at first. Once they'd got a fair distance from the training grounds, and Killua had ensured that no one was listening to the best of his knowledge, he asked, "So what did you want to talk about?"

"I was just wondering if you’d be familiar with the skill Lovro-san taught me so I could ask for pointers."

Killua raised a brow. "Why would you think I’d know whatever it is he taught you?"

"Well… you seem to know a lot of things? So even if you haven’t seen this skill before, I figured you’d still be able to help me."

"Well then you're going to have to describe it to me. Don't tell me he just demonstrated it but didn't tell you the theory behind it."

Nagisa frantically denied it before going on to recite the explanation Lovro had provided him.

Killua hummed for a moment as he assembled a reply in his head. They're almost to the clearing when Killua finally spoke, "Sounds like it requires impeccable timing and ability to read your opponent. Can’t say I’ve really used anything like it, since usually the fight’s over pretty quick for me. I think it’s suitable for you though. Remember what I said about you working best with changing a fight into an assassination? Yeah, this skill seems to fit the bill. Still, it seems like a lot of prep work, and probably works best as a trump card instead of something you use to fight with constantly; it works best if your opponent doesn’t know you can use it. So if all else fails, and you have to pull it out, I suggest acting."

"Acting?"

"Yeah, act weak, unconfident, like they could beat you at any moment. People tend to let down their guard when they think they’ve won, so you can use that to catch them off guard with this ability. Unless they have impressive mental faculties or have encountered this ability before, I’d say it’d work maybe 9 times out of 10."

They reach the clearing when Killua tacks on an extra reminder at the end, "You’d have to not reveal Rhythm Echo though. That tends to put people on guard instead of off guard."

Nagisa was a bit worried that Killua would stop training him, but before he could sink too far into doubt, Killua reassured him that he was still going to teach him how to use Rhythm Echo since it was better to have more cards up his sleeve, finally settling Nagisa's anxious heart.

* * *

After yet another long day of training, Nagisa trudged back home. However, the moment he opened the door to his house, his heart leapt into his throat. The lights were on. His mother was home.

**Notes for the Chapter:**

> For those of you wondering, I mix headcanons with movie canons with anime canons regarding Killua's past, so if you want to know which is which, just quote the section of the story and I'll reply it to you in the comments.


	10. Mother Troubles

**Summary for the Chapter:**

> Killua is the best big brother and you can pry this fact from my cold, dead hands- Alluka/Nanika probably

**Notes for the Chapter:**

> Look, as a disclaimer, all the abuse/PTSD-related stuff I tend to gloss over since I don't have firsthand experience with it. Child abuse especially I find uncomfortable to even read/watch, let alone write. I've also included a lot of my thought process in the end notes, so if you find something inaccurate, I have my thought process down there for you to pick apart.
> 
> Also, I think I've packed too much content in quality, so this chapter's kinda lacking in quantity.

The next day, when Killua and Nagisa met at the foot of the mountain again, Killua noticed that Nagisa was wearing a long-sleeved turtleneck shirt, like the kind he used to wear. Considering the weather and the fact Nagisa knew he was going to be training today...

Killua pursed his lips, but managed to hold his silence until they reached the clearing. Just as Nagisa was doing his usual warm-up stretches, Killua spoke, "We're taking a break today. I'm not having you train while wearing that; you'll get heatstroke."

Nagisa tried to protest, but Killua overruled him, "Look, it's fine if you don't want to talk about home, but I'm not making it worse, got it?"

"I'm fine, really, I can still-"

"Then take off the shirt, better than suffering heatstroke."

Nagisa slumped, defeated. He couldn't take off the shirt, nor could he convince Killua to continue training him. Just as he was spiralling into negative thoughts, Killua gave him a light slap on his head.

"Ow! What was that for?"

"Stop thinking so much. You'll wreck what little confidence you already have."

For the first time he could recall, Nagisa snarked back, "Easy for you to say. You’re always so confident. I don’t know how you do it."

He didn’t notice Killua’s eyes going distant, as if reliving someone else’s words from a different time.

Only once Nagisa noted Killua had been silent for awhile did he turn and look, afraid he'd somehow managed to fuck up with his words, to find his friend with a glazed look in his eyes, something that had never happened before. Worried, he waved a hand in front of Killua’s face (he was going to pat him on the shoulder, but recalled Killua’s aversion to having his boundaries breached), allowing Killua’s eyes to gradually come back into focus, but Killua still didn’t speak.

Feeling guilty for probably being the cause of this, Nagisa blurted out, "My mother has really high expectations of me, so-"

But Killua cut him off, "I don't want you to tell me just because you feel guilty for who knows what reasons. If you're telling me, I want it to be because you feel comfortable enough to do so of your own accord."

Nagisa shut his mouth, stewing in guilt. He couldn't help it. Killua spacing out had really freaked him out, even if he didn't show it, and he couldn't help but link that to the words he said earlier. Had he been too flippant? Had he said something that hurt Killua, even if he hadn't known it would? It was thoughts like these that swarmed Nagisa's mind.

It was when he was wrestling with the 'why's and 'what's in his mind that Killua sighed, and spoke, to which Nagisa turned his full attention on to him (because you do not ignore whatever Killua has to say), "Remember when you asked why I was training you?"

Nagisa nodded, not knowing where he was going with this.

"I… have siblings. Not really close to most of them, especially not the older ones, but I have a younger sister I care about a lot. I… also have a younger brother. You remind me of him"

Nagisa doesn’t know what to say, but just as he’s racking his brains for some way to reply to that, Killua continues after a long pause, "Our mother kept him really close to her, so I didn’t get to interact with him much without her watching. It was different with our sister, since she was closer to my age, we tended to play with each other when we were younger. Then, due to some… extenuating circumstances, I was… unable to care for my younger siblings. Not that I’m saying it was an excuse, but it happened anyway. I only just resolved it recently and went back for my younger sister. I didn’t even think about that brother of mine until later, but by then I learned he’d already left. So, I guess, in a way, I was fulfilling my desire to have been there for him in some way through training you. Not that you aren’t your own person, and I was serious about the other reasons I gave you."

Nagisa is silent for awhile before hesitantly speaking, "You said you wanted me to talk to you because I felt comfortable, not because I felt obligated to. Well, I _do_ feel comfortable around you. My mother… I think she has a lot of regrets, so she’s trying to live her ideal life through me. I don’t like it, but… she’s still my mom. Even though she can be a bit… unstable, I know she still cares for me."

Killua grimaced, which Nagisa notices, to which Killua waved a hand, saying, "Nah, don’t mind me. Just my own experiences colouring my perspective. But what do I know? I stabbed my mother."

Nagisa was stunned. Killua, having been observing his expressions, cracked up and laughed, lightening the mood. "I’m kidding, I’m kidding!"

Nagisa hadn’t seen Killua laugh before, and found that laughter rather suited his friend (though there was a niggling feeling in the back of his mind that questioned whether Killua had actually been joking). He couldn't help but laugh along with Killua, lightening the burden on his heart that had been there since he went home yesterday.

Nagisa couldn't help but reflect that though he'd never had siblings, he felt like Killua was a great big brother to have, even if the person in question didn't seem to think that way.

* * *

Nagisa continued to work on Rhythm Echo for the rest of the week. He was beginning to get the hang of the cadence he needed, though he still couldn't produce afterimages.

The day he first caused his outline to blur, he was so ecstatic he couldn't help but cheer, an earsplitting grin on his face. Killua had given him a nod of approval, and told him that it was now just a matter of practice- though Killua doubted he'd be able to properly use it for the upcoming assassination attempt.

Yes, Killua knew that the island trip was where the assassination attempt was going to be held; it wasn't like the class had even tried to hide it from their _target_. 

Killua himself was sort of looking forward to the trip, curious to see if the island was anything like Whale Island...

**Notes for the Chapter:**

> Skipped over Nagisa and his mother's interactions, so sorry about those who read the last chapter expecting to watch that trainwreck happen. I figured that your imaginations would be far better at painting the picture than my words ever will (plus I assume you've all watched AC).
> 
> [He didn’t notice Killua’s eyes going distant, as if reliving someone else’s words from a different time.]
> 
> For those wondering what moment he’s reliving, please recall Gon’s words at the end of episode 116 and compare it to Nagisa’s. I know the wording isn’t the same, nor is the intent, but people with PTSD can draw unwanted parallels (no, once again, I do not have firsthand experience, just a lot of reading under my belt). For those too lazy to do that, allow me to state here off the top of my head, “You have it easy, Killua. You’re perfectly calm. Since it means nothing to you.”
> 
> I swear I didn’t write Nagisa’s lines with that in mind, the parallels just came to me and I had to go this route.
> 
> I've had the Killua comparing Nagisa to Kalluto scene in my head for so long that I've changed it so many times, and still wasn't happy with it. I also didn't know how to get Killua to open up, so after this popped up in my head, it was like a lightbulb. I'm sorry Killua, but you're gonna have to relive the past.


	11. Island Time

**Summary for the Chapter:**

> Set in the episode with the same name. Felt it was descriptive enough, so I didn't bother thinking of a better name.

**Notes for the Chapter:**

> Whew, I'm almost done with the outline for this fic, thinking I'll end it where the first season ends (since otherwise I'll have to think of ways for Killua to NOT one-shot the Reaper 2.0, which mostly consist of him being not around, which brings us back to my planned ending for this fic). As of right now, I have 13 chapters written in the outline, with 14 planned to be the ending (though maybe 15 if I feel 14 is dragging on for too long). Still, trying to work out how to tie it up neatly is burning through my brain matter, so maybe I'll extend it till I find a nice stopping point. That or start a sequel. Yeah probably that.

A yacht chugged along the wide expanse of ocean, which, since there was no land in sight yet, looked like a giant mirror. It was in the thick of summer, so the heat bearing down on the boat and ocean was rather oppressive. Luckily however, the occasional brushing past of a sea breeze made it tolerable to the passengers on the yacht. There was the occasional crying of seagulls, which declared that despite not being able to see any sign of land, they weren't too far from it. The slow ebbing of the waves, combined with the sunlight and sea breeze, all combined to form the ideal conditions for napping, which a certain white-haired boy was taking full advantage of.

Killua was currently curled up on a deck chair beneath a canopy, dozing off, while Nagisa was attempting to apply his experience with Shadow Step to see if he could execute it despite the rocking of the boat. It seemed he was doing well enough on his own, so Nagisa saw no need to wake Killua from his nap.

A certain redhead, on the other hand, saw this as the prime opportunity to prank the usually alert boy. A devious grin on his face and a marker in hand, Karma crept up from a direction that he reckoned the occupied Nagisa would be unable to see him and thus alert the sleeping Killua. However, he hadn't even gotten within a meter of Killua before the other boy's eyes snapped open, and that cerulean gaze had him pinned in place, as if assessing a threat. It was only once a glimmer of recognition shone in those eyes that he didn't feel quite so much as if he was being visually dissected.

Karma hid the marker behind his back and whistled innocently, causing Nagisa, who had noticed him by this point, to sweatdrop. Knowing his friend (ex-friend? Or was it just classmate at this point?), Nagisa could tell that Karma had attempted to do something to Killua while he slept. And it seemed Killua did too, if the mix of annoyance and general unamusement in the look he shot Karma was any indication.

Attempting to mediate before any conflict truly started, Nagisa spoke up, "Killua, have you ever been out on the sea like this?"

Killua looked at him, knowing full well what his intent was, but deciding to humour him anyway, and spoke, "Yeah, a couple of times I guess. Since my best friend lives on an island and all."

Nagisa and Karma looked interested. They'd never heard Killua mention anything about having friends outside of E Class, which would have been concerning, but they were the End Class no one wanted to associate with, so it was understandable. It was more surprising to hear that he actually had a friend outside of E Class, someone he considered his best friend in fact, despite the fact that none of them had ever seen Killua with, or heard Killua even mention them. Karma, being the bolder of the two, was the one to voice the question they were both thinking, "Oh? Now I’m curious as to who managed to snag the ‘best friend’ spot."

"A reckless idiot."

When Killua didn't elaborate, Karma looked like he was about to push for a more detailed answer, but Nagisa, having noticed that Killua looked similar to how he had when he was recalling his past (not exactly the same, thankfully, at least his eyes weren't glazed over), pulled Karma back. He dragged Karma out of earshot (at least, he believed it was out of earshot—you could never tell with Killua), with the latter surprisingly not putting up any resistance.

"Ne, Nagisa-kun, what'd you drag me away for? Do you know something I don't?"

Nagisa rubbed the back of his head. "Not really, I just felt it was a sensitive subject for Killua, so I didn't want you pushing him, I guess?"

Karma cocked a brow, mulled it over for a bit, then decided if he wasn't allowed to push Killua, then at the very least he could squeeze some answers out of Nagisa. Poor Nagisa ended up getting dragged off to be interrogated (bless this loyal kid; he didn't reveal anything too private even with Karma being the one grilling him for information).

* * *

Meanwhile, Killua was having a stroll around the deck since his nap had been interrupted. He spotted their motionsick teacher, as well as the class' continued failures to kill him despite that, and couldn't help but shake his head and continue on, taking a route that avoided people.

As he stared at the metal and plastics that made up the yacht, his mind couldn't help but remember a different boat trip, one made on a wooden boat. Despite the yacht having a more modern design, with more amenities he could use to occupy his time as a result, he couldn't help but feel like he was having less fun on this trip than the one he remembered. It was at this point that the back of a certain person flashed in his mind. He could almost picture their brilliant smile and the laughter in their voice as they called his name.

Fond, if nostalgic memories bubbled up in his mind. Like the many times the two had raced each other, for no other reason than the thrill of it, a sharp contrast to the dull monotonous training from before, where 'races' were pretty much only to measure his progress. Like all the times the two only had to share a look for the other to know what they were thinking, whether it be a silent challenge to a competition, or a battle plan. Like the time that person had jumped off a cliff, and Killua had merely paused long enough to decide how he should jump (headfirst or feetfirst?) before leaping off after him.

At some point during his reminiscing, Killua had made his way to the highest vantage point on the yacht, his footing steady despite the constant rocking. He stayed there for a good while, to the point where a hint of land had appeared on the horizon. As he watched it come into view, his heart couldn't help but sink in disappointment that it wasn't the familiar shape of the place he'd made so many happy memories, but he scolded himself, saying that he'd already known that, so why was he still so disappointed?

Even once they'd docked, Killua was still lost in thought, hence he didn't pay all that much attention when drinks were offered to the students, simply taking one and drinking it. By the time everyone had gotten settled in though, Killua had mostly recovered back to his usual state of mind.

Nagisa and Karma approached him, asking if he'd like to go with their group despite not helping with the prep for the assassination later tonight. Killua agreed.

* * *

As the group of students he was with watched the gliders circling around in the sky, Killua noticed that one in particular appeared to be more like a giant bird, what with the speed and maneuverability it displayed, and came to the conclusion that that was the one the octopus was piloting.

When it came time to dive in the sea, Killua pulled on his scuba gear, despite knowing that he could hold his breath for a long time (though he lived on a mountain, his family prided themselves on being the best in their profession, so he was naturally trained to endure all sorts of extreme environments), since he didn’t want to stand out. He had gone diving before with Gon, when he visited Whale Island, but he noticed that the marine life here was different, and couldn’t help but think that Gon would’ve loved to be here too.

The day passed by with various different activities, with Killua occasionally hopping from group to group since he was the only one who wasn’t participating in the prep, so if he felt bored with one group, he usually just bid them farewell and went to see what the other groups were doing. Still, despite his lack of active participation, this hopping around from group to group managed to have him act as a messenger of sorts, allowing the groups to coordinate better, so no one had any issue with it (except Terasaka, but that’s because he’s still salty).

* * *

When evening finally came around, the whole class gathered on a boat to have their dinner, with Killua and Nagisa having found a table together. Killua wasn’t eating chocolate, instead he had all sorts of fast food piled up on his plate. Nagisa wasn't sure if this was preferable to the chocolate... Both were pretty unhealthy, but it wasn't like he'd be able to get Killua to listen about eating healthier when even the mother hen Korosensei failed, so he tried his best to focus on his own dinner.

Karma came over to sit with them, since he didn't really have a fixed group he hung around with, and the only ones he'd hang around with on a consistent basis were Killua and Nagisa anyway. Nakamura was more of a... partner-in-crime, but there wasn't any 'crime' to be committed right now.

It was then that all three of them had front row seats to their teacher committing the dumbest move of a century—he used his once-a-month ability to shed his skin, just to get rid of a sunburn, essentially hobbling himself, and right before an assassination at that. Even Killua couldn't help a snort from escaping as he found himself agreeing with the person wondering how they hadn't managed to kill this idiot yet.

Karma and Nagisa made some small talk with Killua by asking what he was going to be doing while they were busy with the assassination, to which he hummed, before replying, "I guess I'll be hanging out on the pier and watching from there."

"Man, kinda wished you participated just so you could watch the blackmail video we've got on him." The speaker was naturally Karma.

Killua shrugged. "With how he usually acts, wouldn't be too hard to get more. Besides, even if you guys succeed, you could just let me have a look before destroying the evidence."

**Notes for the Chapter:**

> This chapter was more of a filler and set-up chapter, just like the episode it was named after. Won't really go into detail with the assassination, since, like I've said before, I assume everyone reading this has watched AC.


	12. Trouble in Paradise

**Summary for the Chapter:**

> The assassination attempt goes as well as in canon, and so does the aftermath.

**Notes for the Chapter:**

> I know you guys were wondering if the assassination attempt would change due to Killua's presence, but honestly my brain is already fried trying to fit together events while accounting for Killua's presence and trying to wrangle the story in the direction I want it to go, so I left the attempt as in canon, since I felt the canon attempt was actually quite enjoyable, and there wasn't much I could do to improve it.

The assassination was scheduled to be held at night, which Killua felt had some safety problems that came with it, seeing as it was way too dark to be risking being on the sea (granted they weren't going that far out). Which was why he was currently seated on the edge of the wooden pier, a motorboat having been tied up nearby for ease of making rescues if needed.

Killua's legs swung back and forth as he watched the wooden structure, his gaze scanning the boats his classmates were waiting on to make sure that he'd be able to catch if anyone fell off and needed help. Contrary to what his cool exterior would have you believe, Killua was an overthinker and a worrywart, a combination that was only kept somewhat in check by his desire to not act like his family. Still, one of the only reasons why Killua hadn't done his best to change the plan to be safer for those involved (excluding their target, of course) was because he knew they'd all learned how to swim after the Pool Incident, and so would be able to hold out for long enough for him to go fish them out.

The breaking apart of the wooden structure caught his attention. It meant that the plan was starting. He paid closer attention.

As columns of water erupted into acting like the bars of a cage, Killua whistled as he saw the figures of his classmates balancing on top of them. Sure, he knew this was part of the plan, but seeing it was another thing altogether. Honestly, had any of them shown a similar propensity to stealth as Nagisa, he'd probably have taught more of them; they already had the balance part down pat after all.

However, when the explosion happened, he shot to his feet, his mind racing a mile a minute as he untethered his motorboat, hopped on, and directed it towards his classmates, hoping that none of them had been hurt.

Nearing the area where the wooden structure used to be, he saw several floating pieces of debris and the heads of his classmates bobbing to the surface. After a quick headcount, he noticed that everyone (except for their target) was accounted for, and didn't appear injured, just stunned. Releasing a sigh of relief, he gestured for the others on motorboats to help him with fishing out their classmates and ferrying them back to the pier, which was closer than the shore. He himself drew his yo-yos and started fishing the closest ones out.

Not everyone could be brought back in one trip, so those in the boats had to go back again to grab everyone. Luckily, it was fairly organised with Killua directing them where to go to be most efficient.

By this point, Killua noticed that Karma had a small, clear ball that seemed to be containing their teacher/target (a Koroball?), but figured the questions could wait till everyone was out of the water and had gotten changed out of their wet attire. Once everyone was out, he began herding them back to the resort to get changed so they wouldn't catch a cold. Their bodies' immune systems were weaker than his after all.

On the way however, he noticed that some of them seemed to be flagging. He frowned, but put it down to it being a combination of exhaustion from the recent assassination attempt as well as the mental hit of the failure of said assassination attempt. He himself was feeling a bit tired, which was odd, given that he could go several days without sleep and only just start to feel tired, but he brushed it off as worrying too much (to which he resolved to eat more chocolate to reward himself for his hard work). 

However, the class didn't seem in a rush to get changed as everyone gathered together. Now, the depressed atmosphere was even more obvious, pretty much everyone (except Killua) having long looks on their faces. Not for the first time, Killua wished that his best friend was here. Gon would've known what to do to cheer them up, while Killua... didn't.

Killua furrowed his brow. He wanted them to get changed before they caught a cold, but they all looked so exhausted... It’s at this point that the first person topples over, immediately catching Killua’s attention. One after another of his classmates start falling, and he notices that some of them show signs of running a fever. His first thought was that they’d come down with a cold due to being soaked in the sea at night, but that thought dispels itself after Okajima comes down with a nosebleed. That was definitely not a symptom of your common cold.

Karasuma and Korosensei both appeared worried, but the former didn't get the most favourable answer when he asked where the hospital on the island was, while the latter was stuck in his Absolute Defence form and was thus unable to move.

When the phone call came on Karasuma's phone, at first, Killua didn't pay that much attention, simply assuming it was Karasuma's superiors calling to check in on the results of the assassination attempt, but then the abnormally deep voice came through, sounding like... like the result of a voice modifier. _That_ caught Killua's attention.

What they said clarified what was going on—his classmates had been deliberately dosed with an artificial virus. Killua frowned. Viruses... were a bit different from your regular old poisons since they could adapt. Sure, he was immune to a lot of viruses, but it was impossible to be completely immune simply due to the nature of viruses. Luckily, after being put through so many different kinds of toxins, poisons, and what-have-yous, his immune system was more robust and adaptive than that of the average person, so he wasn't worried about himself.

However, when the person specified that they had to send their two shortest males (Killua and Nagisa are both 5'2, I looked it up) to the top floor of the hotel within an hour, Killua's frown deepened. That was a very specific request.

After Takebayashi confirmed Killua's thoughts that getting their classmates to a hospital would be too risky and would take too long, he sunk back into thought. In the worst case scenario, they _could_ try using his blood to make an antidote, but that came with it's own problems. For one thing, it might take too long, and with time being one of the main constraints, Killua was hesitant to do so. And he couldn't just use his blood straight out, because his immune system was _too_ robust and might attack the cells of the people it was donated too along with the virus. The cherry on top was that it would definitely reveal he wasn't normal (though he was perfectly willing to blow his cover if he had any sort of guarantee it would work). As a result, Killua shelved that plan as a last resort.

It was at this moment that Ritsu spoke up and Korosensei explained his plan to them. 

* * *

The class faced a cliff wall that was taller than anything they'd ever scaled before (shush Killua, you don't count). The sheer height of it was enough to intimidate any rookie rock-climber, let alone the fact that they'd have to scale it without any climbing apparatus to assist them.

Just as Karasuma was about to call it quits, the class started to climb the cliff. Killua was one of the faster ones, but he deliberately slowed himself down to be able to watch out for his classmates and catch any that might slip. He would've carried one of the slower ones, but after some deliberation, figured that he wouldn't be as capable of catching any who fell if he had someone on his back, so he could only scrap that plan.

He didn't have to worry though, as it seemed most of his classmates were making pretty good headway up the cliff. Ironically, it was the teachers who were in most danger of falling, what with Karasuma being stuck carrying both the Koroball (which wasn't heavy, but said person was very distractingly annoying) and Irina (who was complaining about the ride not being smooth enough). Killua was stuck between feeling amusement and pity for Karasuma.

In the end, after some directions from Killua and, surprisingly, Karma, the class managed to scale the cliff without injury and in a decent amount of time.

Once they entered the hotel, the class noticed that the lobby was swarming with guards. Just as Killua was contemplating whether he should reveal his hand and knock them all out, to his surprise, Irina strutted out and seduced all the guards by acting as a tipsy pianist.

Killua admits to himself that he's not really familiar with her version of assassination since none of his family used _seduction_ as an assassination technique. Just the mere thought of any of them doing so was enough to send shivers up his spine (it'd be like living with a family of Hisokas). This thought creeps him out so much he only notices the approaching person much later than he usually would.

Terasaka and Muramatsu had cockily rushed forward and would be within range of an attack. Now, there were several options Killua could take here. One, he could use his yo-yos to yank the two back. This would let him get them out of the way without putting himself at risk. However, he had no idea if the incoming hostile had any method to communicate to their boss, so it was best if he minimised information about his abilities. The second option would be to let Terasaka and Muramatsu get hit while pulling Karasuma back. This would be a more optimal strategy, if it wasn't for the fact that Killua was loathe to let his classmates suffer an unknown attack (yes even one as annoying as Terasaka), not to mention the possible time wasted due to an argument afterwards. Lastly, Killua could help save one of them so Karasuma wasn't as directly in the line of fire, and if it was a targeted attack, Killua would be able to halve the chance that Karasuma would be targeted just by being one of the targets (what he was banking on was him being attacked, since Killua was confident he was the tankiest out of everyone present). All these thought processes passed through Killua's head in the blink of an eye, and he'd already made his choice before even a second had passed.

Killua launched himself forward and shoved Muramatsu out of the way at the same time Karasuma shoved Terasaka out of the way. Luckily, Karasuma had noticed Killua coming and so had managed to pull himself back from crashing into the boy. Unluckily, the man had just launched an area of effect gas attack on the both of them.

Whereas Karasuma was briefly knocked out, Killua only experienced a mild dizziness for a moment before he adapted to it. Despite this, he didn't move other than to sway slightly, acting the part of someone who'd been affected, though less so than Karasuma, in order to lure the poisoner into a false sense of security. Meanwhile, Fuwa was doing her detective schtick and deducing that the drinks that had been given out earlier in the day were spiked. Killua is just about to knock out the guy when he turned to leave, but noticed his classmates blocking all the exits, and then Karasuma getting up.

Figuring he could still afford to hold back, Killua shoved his hands in his pockets, hiding the fact that they'd shifted into claws. If he was fast enough, he'd be able to subdue the poisoner without giving it away, unlike his yo-yos. The only issue was hiding it from his classmates. Normal people couldn't exactly turn their hands into claws, y'know?

However, it turned that he didn't need to worry, for Karasuma was able to resist the effects of the poison long enough to knock out the poisoner. Killua was able to relax, allowing his hands to revert back to normal.

It was at this point that Nagisa approached him. The other boy's brow was furrowed with concern, but before he could say anything, Killua was already speaking, "Don't worry, I'm fine. I held my breath before he launched that attack."

_'Luckily he wasn't around when I drunk the drink that was given out. The only one here who could blow my cover is the big oaf, but I doubt he was paying enough attention back then to notice.'_

* * *

Nagisa wasn't the only one worried—the whole class had seen him suffer that gas attack after all. But after multiple reassurances from Killua that he was fine, they dropped it.

Just as the class was getting ready to continue on their way, Killua suddenly spoke, "You guys go on ahead. I'll catch up after I've tied this guy up better and stuffed him in a better hiding spot."

The class didn't have many people experienced with this sort of thing, and those who were (the only two teachers with them) were either incapacitated or already struggling just to walk, let alone tie up loose ends. And there was only so far instructions would go to bridge the experience gap.

Truth be told, someone should have been left behind to watch the captive, but it had been decided that the whole class would continue on due to a few reasons. For one, anyone left behind would have been in some danger due to the risk that the poisoner would wake up and manage to free himself or that one of his buddies would manage to stumble onto them, thus making them a potential hostage. There would be danger in continuing to infiltrate too, but at least then they'd have the rest of the team to back them up. Secondly, they had no idea what sort of obstacles they would be facing ahead, and by extension, whose skills they would need, hence it was best to bring the whole group.

Hence, when Killua brought this up, it naturally raised some concerns, especially over his safety by leaving him alone with a trained hitman. However, the calm confidence he radiated, along with more reassurances and their already present knowledge that he was skilled (even if they didn't know to what extent), was enough for them to trust him to do this on his own. On the teachers' minds were also that he could use this chance to recuperate slightly (they hadn't bought the line he told them about managing to hold his breath in time—they knew he was just saying that to reassure them).

After the rest of the class left, Killua got to work, doing a proper search of the poisoner to find several vials, as well as several loops that looked as though they were used to hold similar devices to the one he'd used to launch the poison gas attack from before. Killua frowned slightly; from the looks of it, he should've had three. He'd used one, and Killua had noticed that Karma was one of the ones who tied this guy up initially, so the whereabouts for the second were pretty easy to guess, but what about the third one?

Killua hoped that Karma had come to the same conclusion and was on guard for one of the poisoner's buddies being in possession of it...

Killua swiftly trussed up the poisoner in more secure restraints and went looking for somewhere to hide him. He found a broom closet that was fairly out of the way—perfect for his needs. It wouldn't be enough to keep the guy hidden for longer than a couple hours, but it wasn't like this infiltration would take that long, given the time limit.

With a small amount of annoyance, Killua noticed that his temperature had risen slightly. Whatever that virus was must've been pretty potent to affect him this much, which only raised the concern he felt for the others.

* * *

Having finished tying up loose ends, Killua hurried to catch up with the rest of his class, arriving just in time to see Karma swinging a potted plant at someone who looked like a delinquent, but radiated the familiar aura of a killer.

Killua silently approached, noticed perhaps only by Korosensei (since the latter could only pay attention to his surroundings right now, while the rest were a bit more distracted by the fact that one of their number was engaging a hardened killer in combat), and positioned himself somewhere he'd be able to intervene if need be. Killua wasn't a big stickler for things like honour and not interfering in one-on-one fights, but figured that Karma could use some experience fighting a more experienced opponent, which was why he stayed his hand and watched.

Killua observed as the man lunged and grabbed at Karma, deducing that the man's weapon was his bare hands. However, the man wasn't like him, in that he could make his hands literal weapons, but more like... what was the name of that one guy? The guy whose heart he ripped out back in Trick Tower? The only reason he remembered the guy at all was because of his excessively extra introduction of digging a furrow into the wall. Wasn't he a mass murderer or something?

Killua shook his head, focusing back on the present. Karma was nimble and agile enough to dodge, so Killua wasn't really worried (says the person who's keeping a tight grip on his yo-yos). When the man hunches over, Killua's eyes narrow, knowing that he's planning something. He hopes that Karma has come to the same conclusion, otherwise, experience or not, he was going to interfere.

As expected, the man whirled around, pointing one of those devices from earlier and sprayed gas in Karma's face. Killua watches, eagle-eyed, as the man picks up Karma by the face, and just as he was about to interfere, sees Karma's hand in his pocket, and relaxes.

It seemed that Karma's counterattack had caught everyone else off guard, including his opponent. Yet it seemed like the big guy was pretty resistant to the gas, for he still put up quite a fight, granted Karma managed to restrain him without much trouble.

Once the fight was over, Killua sauntered up and knocked out the still struggling assassin, his presence only now being noticed by the rest of the class. With practiced ease, Killua tied up this one too, though he couldn't help his eye from twitching when Karma started tormenting his former opponent. Most of the class' attention was drawn away by this, but the teachers had noted the familiar way Killua had trussed the assassin up, as if he'd done this hundreds of times before.

Killua takes on the task of properly securing this guy too. The class was reassured since he'd come back perfectly unharmed from taking care of the last guy, so they let him do so without much fuss.

* * *

It took much longer to find a place to securely stash this captive away, since he had been positioned in an open corridor (a strange place to put _any_ guard, let alone one who was at their most effective when remaining hidden).

Just as Killua was questioning the intelligence of the mastermind behind this plan, the rest of the infiltration team had reached a terrace and bar area. Some of them would have to go through it to unlock the door for the rest of the team, and it was agreed that letting the girls go would be for the best, since they'd raise less suspicion. However, Karasuma (like the dad he was) worried about their safety, expressing that he'd prefer that they were accompanied by at least one guy.

At this, a devious smirk stretched across Karma's face as he eyed Nagisa, the latter feeling a shiver go up his spine. _'It's just a shame Killua isn't here too...'_

Back with Killua, he too felt an inexplicable shiver run up his spine, as if he'd barely managed to escape some horrible fate. Shaking it off, Killua resumed his search for a hiding spot. Though if he was a bit slower this time... well, there was no one else here to call him out now was there?

* * *

When Killua finally caught up with the rest of the class, he found around half their number (mostly the girls, but for some odd reason, Nagisa wasn't there too). Concerned, he inquired about their whereabouts, to which Karma flashed him a picture of... was that Nagisa?

Luckily, someone else explained that the girls were heading through the bar to unlock this door from the other side, while Nagisa had gone along for... security reasons? Honestly Killua felt it more likely the girls would have to protect Nagisa... That wasn't to say he didn't have the skills to protect himself—he just had the type of personality that let others walk all over him if they didn't cross his bottom line. Karma had wisely not mentioned his previous musings (he might want to fight Killua, but now was neither the time nor place), though it didn't stop a suspicious Killua from eyeing him.

When the girls finally return with Nagisa in tow, Killua watched as Nagisa took off like a bat out of hell to get changed. He sighed, having guessed just from that that Nagisa disliked crossdressing, so he must've been pressured into it, the most likely suspect being the devilish redhead standing next to him.

When Nagisa returned and lamented the fact that he hadn't been of any use, Killua shook his head as yet another of his guesses was confirmed. He watched as the other boys teased Nagisa, and the latter getting more uncomfortable. Without thinking, Killua patted him on the head comfortingly (though secretly he tensed up afterwards, wondering if he'd crossed a line). Luckily, it seemed to have the desired effect on Nagisa, whose ruffled feathers appeared to have been smoothed down by that. Korosensei noticed this, his ever present grin growing wider.

**Notes for the Chapter:**

> In case you wonder why I call Irina by her given name rather than 'Bitch-sensei', it's because I feel uncomfortable calling her that, blame my manners. And if you're wondering why I don't put her last name, it's because it requires accents that are annoying to put with my keyboard. Therefore, her given name is the best (plus she's a foreigner, not Japanese, so referring to her by her given name isn't as rude as referring to a Japanese person you aren't familiar with by their given name).
> 
> These next few chapters are going to be pretty long by the way, they already take up way more of my outline than I was expecting, but that might just be because I can't help but add details and revise stuff over and over since this is the climax of the arc.


	13. Dungeon Crawl (Tower Crawl?)

**Summary for the Chapter:**

> Killua finds his calling as a 'janitor', while the rest of E Class gain XP by beating mobs and mini-bosses. And then it's time for the final boss... and a surprise encounter.

**Notes for the Chapter:**

> Does the chapter summary sound like Shigaraki ghostwrote it? Yes. Am I going to change it? Probably not.

Noticing that their path was obstructed by yet more guards, Killua nearly sighed. At least these ones didn't appear as skilled as the previous ones, so he didn't even consider acting unless his classmates were really stuck.

When Korosensei told Terasaka to use his 'hidden weapon', Killua's brows nearly disappeared behind his fringe. It was a good thing Terasaka hadn't been looking at him, for he probably would've thrown a fit.

Terasaka drew a couple of familiarly shaped objects, resulting in a glimmer of interest appearing in Killua's eyes. With Mimura acting as bait to lure the two over, Terasaka and Muramatsu used these devices to shock the guards, confirming Killua's guess as to what they were. After a brief search of the two guards, the class managed to find a couple of revolvers, which ended up being handed to the two shooters of the class. Killua saw no problem with this, but figured that now was the best time to raise his request.

The class was mildly perplexed as to why he wanted one of the stun guns, but after he pointed out they’d still have the other one, plus the two revolvers, and the fact that it was better to play it safe since he’d have to hide _two_ people this time instead of one, they figured it wouldn’t really hurt to let Killua have one of the stun guns for now. The explanation didn’t convince everyone (especially not those who had more knowledge about Killua's skills), but it wasn't like they had a real reason _not_ to let him have one of them, seeing as they'd still be more armed than they were previously.

After the rest of the class had gone on ahead, Killua set to work finding a place to hide the two, having it easier this time because there were plenty of rooms around. That done, he drew out the stun gun he'd borrowed. _'I should recharge in case I need Godspeed. Probably won't, but better to be safe than sorry...'_

Without hesitation, he brought the stun gun down on his bare arm.

* * *

By this point, the rest of the team had already run into Gastro, who was currently taking potshots at them. Luckily, thanks to Korosensei's instructions and misdirection of the assassin, they were able to sufficiently confuse him enough for him to misjudge where the ones with guns were. 

It was after they had managed to disarm Gastro and pin him underneath a metal structure that Killua came running in, having heard the gunshots when he was on the way. It didn't seem like anyone had noticed, but just as he was coming within view, sparks of electricity fizzled into nothingness. It was only after taking a headcount and doing a quick sweep of everyone (and finding no visible injuries) that Killua was able to relax slightly.

Still, he approached Nagisa anyway to ask if anyone had been injured, and it was only once Nagisa had confirmed that no one had been injured that Killua was able to completely relax.

Killua then approached Terasaka to return the stun gun, before heading over to the downed Gastro and searching him, coming up with several more guns. He handed them out to the rest of the class, but it seemed the rest of them weren't as confident in their ability to use a real gun as Chiba and Hayami. Killua shrugged, and told them to keep them as a backup plan.

By now, Killua was pretty much the designated clean-up guy for the class' takedowns, so as usual, the class went on ahead, leaving him behind. Sighing, Killua shook his head, thinking to himself that he hadn't seen much action. _'Ah shit, I jinxed it, didn't I?'_

* * *

It didn't take Killua too long to hide Gastro, as the amphitheatre the shootout had occured in had plenty of seats which could act as a decent hiding spot. That, and they were already nearing the top of the hotel, so there wasn't any need to go out of his way to find a separate room. Hence, Killua managed to catch up with the rest of the infiltration team just as Karasuma was taking down another guard. From the floor plans, it seemed like the person they were looking for would be behind this door, so Killua felt like he (probably) didn't need to clean this one up. 

He noticed Nagisa talking to Terasaka off to the side, and due to the latter's less than stellar track record with the former, decided to get closer. Look, just because he had sharper hearing doesn't mean he was eavesdropping okay? It _just so happened_ that he heard them talking.

It was thanks to this not-eavesdropping that he learned Terasaka had drunk some of the spiked drinks earlier today, and was currently fighting the effects. What really surprised him though, was when that dumb oaf revealed he'd been more observant than Killua thought, when he revealed to Nagisa that it wasn't like he was the only one on this mission who'd drunk the spiked drinks.

Killua's snort announced his presence to the two, both of whom turned to look at him, one in annoyance, and the other in concern, having probably guessed by now who Terasaka was referring to. Knowing he wouldn't be able to convince Nagisa otherwise, Killua spoke first, "I'm fine. Really."

"But—"

"Though the big oaf should take it easier."

"Hah?! What did you call me?!"

Terasaka's angered exclamation drew the attention of the rest of the class, who only now noticed his unusual complexion. "Hey, man, you doing okay? You don't look so good."

"I'm fine!"

"Shit man, don't tell me you're affected too! Why'd you still come?"

"You really should take it easy, man."

In a mix of anger and annoyance, Terasaka pointed at Killua and blurted out, "He drunk it too! Why don't you guys tell _him_ off, eh?"

As one, the class turned to look at Killua, who appeared about as unaffected as you could be. Then again, it wasn't like anyone had noticed Terasaka being affected until now, so maybe it was just taking longer to set in?

Killua's lips were slightly upturned as he spoke, voice coloured with a tinge of amusement, "All I did was save a certain idiot duo and help with the clean up. Wasn't straining myself, unlike you."

Thinking back on it, the class recalled that it was true. Now that they knew Killua at least knew not to push himself, they turned their attention back on Terasaka. Nagisa, on the other hand, wasn't so easily redirected, having gotten used to Killua's habit of turning attention away from himself at this point. "Are you sure you're okay?"

Killua sighed, knowing the other boy wasn't going to let up unless he gave him something more concrete, so he leaned in and spoke in a low voice so that only Nagisa could hear, "I’ll tell you a secret: I’m immune to most poisons. That kinda extends to viruses too, by the way. It's just that this particular one happens to be a bit stronger, but it’s nothing I can’t handle. So stop worrying, got it?"

Nagisa blinks in surprise at what he just learned. It doesn’t stop him from worrying, but he can tell that Killua didn’t like it when he worried, so he kept his mouth shut. Still, he wonders when (and more importantly, _how_ ) Killua had become immune to poison. It also has him a bit worried for the rest of his classmates because if even Killua could feel the effects, and he claimed to be mostly immune to them, then the rest of his classmates, including Terasaka…

His musings were interrupted by the rest of the class having decided to continue on instead of wasting their energy trying to convince Terasaka when they were running on a time limit. Now that they were only one room away from where the mastermind was supposedly residing, the rest of the team was tense with anticipation. Killua trailed along behind them, so as to not have overly concerned classmates telling him to hang back, resulting in him having to walk next to a sulky Terasaka. 

The latter eyes him before bluntly asking, "Why don't you look affected at all, eh?"

Killua, rolled his eyes, and replied, "I am. Just doesn't show."

Terasaka felt like calling bullshit since he himself was much larger so the virus should've taken longer to affect him. That's how viruses work right? Given that Terasaka knew his own academic abilities... he didn't voice it, so as to not look like an even bigger fool.

While the rest of the team filed into the room (near silently, to Killua's pleasant surprise), Killua scanned the room, taking note of possible hiding spots that any ambushers might be hiding in. He had noticed the person sitting in the chair, but as had been drilled into him from his early training, focused instead on making sure they wouldn't be jumped. When he found out there weren't any hidden ambushers, Killua sighed internally, wondering at the competency of the mastermind if they didn't even have people in the same room to watch their back. Well, there was the possibility that the person in the chair _wasn't_ the mastermind, and was just some mook, but Killua found it unlikely.

It was at this point that the person started scratching at their cheeks and muttering something in a voice that Killua found vaguely familiar, but couldn't quite place. It was only when the man stood up and turned to face them that Killua recognised him. He blinked, his first thought being, _'Well, that explains the incompetence.'_

Akira Takaoka looked at the class with the deranged eyes of a madman.

* * *

It turned out he wasn't so incompetent as to not have any form of insurance, as he soon revealed the fact he had several detonators in preparation for Korosensei's speed. Killua's eyes narrowed. He knew he wasn't as fast as their teacher, even with Godspeed, but he felt he could confidently say his reaction speed was faster. Still, it was up in the air whether he'd be able to defuse the bomb before Takaoka could react and set off the detonator. Hence, he decided to bide his time for an opportunity where he'd have a greater chance of success.

When Takaoka revealed his plan to tie up Killua and bury him with Korosensei, Killua had to fight hard to not show any of the amusement and annoyance he was feeling. Honestly, this joker was going to be death of his poker face. His classmates, on the other hand, didn't seem to find it so funny, all of them with serious expressions and scowls on their faces.

Killua's annoyance won out however, when Takaoka demanded that Nagisa fight him one-on-one. He traced a finger along the edges of his yo-yos. It was then that Nagisa shot him a look and subtly shook his head. Killua raised a brow slightly. _'Huh, either I'm getting rusty at hiding my intentions or this guy's got a feel for my moods already. Not sure which I prefer honestly.'_

Despite Killua's desire to smash Takaoka's head in with a fifty-kilo yo-yo, he could respect Nagisa's desire to do this on his own, so he watched as the two ascended a staircase to a helipad. However, his restraint was tested when Takaoka blew up the bridge connecting the two platforms. Killua's nostrils flared and he started looking for a way over that wouldn't alert either party to his presence. He spotted a small outcropping that one wouldn't think could support the weight of a human, and was way too far for any normal person to reach. He reckoned that it was better if he went for it, even if he were to reveal he was more capable than he let on, pretty much the only downside now would be that he'd be risking more harassment by his classmates. Without bothering to weigh the pros and cons any further (especially not with Nagisa having to face that bastard alone), Killua leapt, silently managing to hook onto the edge of the outcropping and pulling himself up almost effortlessly.

The rest of the class only noticed when Killua was already in the air, so they couldn't convince him otherwise. They watched as their white-haired classmate leapt, grabbed onto the ledge by his fingers and _somehow_ manged to pull himself up. All while being completely silent. It was fascinating, and his movements almost reminded them of a cat's. If the situation hadn't been so dire for Nagisa, they probably would've burst into applause. Now that Killua was in a position to help Nagisa though, the class was able to relax, ever so slightly, knowing that their white-haired classmate would do everything he could to keep Nagisa safe.

As for the two teachers, they had once again confirmed their suspicions that Killua had been holding back the whole time, and could only hope that whatever else he was hiding would be enough to get everyone out of this mess unscathed.

Meanwhile, Killua had used the outcropping as a boosting point to reach the very edge of the helipad, dragging himself up so that only his eyes were peeking over the edge. When he saw Nagisa bowing down to Takaoka, he couldn't help the flash of rage that he felt, but he forcibly calmed himself down, since he'd been the one to tell Nagisa to act weak when in doubt. However, Killua wasn't able to react in time to Takaoka blowing up the briefcase full of the antidote.

Killua dragged himself up the rest of the way now that Takaoka was too busy gloating to pay attention. He hid himself behind one of the stupidly bright lights (honestly that man's IQ fluctuated more than his moods). Killua hoped one of the vials he looted from the poisoner contained the antidote, but if it didn't there was always the last resort plan... Just as he was getting ready to bail Nagisa out, Takaoka revealed that he had several vials of antidote on his person, and though they wouldn't be enough to cure everyone, it was their only option.

Killua's eyes narrowed as he weighed the pros and cons. On the one hand, having more of the antidote on hand would increase the likelihood they'd be able to reproduce it in time to save those who'd been affected. On the other, Takaoka _could_ be lying and all the antidote could've already been blown up. In the end, Killua came to the conclusion that letting Nagisa fight while he searched for an opening to knock Takaoka out in one hit would be the best course of action.

However, it's at this point when a sudden spike in bloodlust appears and Killua swiftly identifies the source to be Nagisa. Now he was in a bit of a conundrum: it would be safer to continue with his original plan, but he had no way to even communicate it to Nagisa in the first place, and the latter looked like he was ready to kill right now. Sure, Killua didn't mind this bastard dying, but he was a bit concerned about what it would do to Nagisa's mental state if he was the one to do it.

It's at this point that Terasaka throws one of the stun guns at Nagisa and yells at him to not sacrifice his future just to kill one bastard. This calms Killua down slightly, as now Nagisa had a nonlethal method of incapacitating Takaoka on hand. Killua noted that Nagisa had placed the stun gun in his belt, seemingly not planning to use it, but recalled the set-up for the skill Lovro had taught him. Despite all of this, Killua still readied himself to act if at any time he thought Nagisa was going to follow through with a murder, even if he had to kill the guy himself to do so.

As he watched Nagisa being beaten up, Killua ground his teeth as his muscles tensed more and more like a spring being coiled, ready to be released in a burst of explosive energy. Finally, Killua senses that Nagisa is about to really make a move, and all his senses go on high alert.

He watched as Nagisa approached Takaoka and dropped his knife, the latter's eyes inadvertently continuing to follow the knife's descent. Nagisa then clapped, stunning Takaoka long enough for him to draw the stun gun and shock him with it.

However, just as Nagisa was about to finish him off with another round of electricity, a bright flash of light, brighter even than the stupidly bright lights the helipad was surrounded in, drew everyone's attention to the sudden appearance of two figures.

**Notes for the Chapter:**

> How many people saw it coming?


	14. Unexpected Arrivals

**Summary for the Chapter:**

> Takaoka makes the worst decision of his life, and considering this guy kicked Killua of all people, that's saying something.

**Notes for the Chapter:**

> I want you to know that I am a diehard Killua simp, and as a result I would never plop his brother and "brother-in-law" right in the middle of the fight. Preferrably they never show up in any of my works except as flashbacks to canon. *shudders*
> 
> Was a bit stuck on the how I wanted things to go, plus I had midterm exams coming up, so this chapter didn't go up as quick as the others despite the outline being done.

The sudden appearance of these two figures distracted Nagisa enough that Takaoka was able to kick him away. Takaoka turned to look at the new arrivals, a crazed look in his eyes as he charged at them, attempting to take hostages to turn the situation back in his favour.

But it was at this time that a wave of bloodlust that dwarfed even Nagisa's erupted forth, locking Takaoka's limbs in place. Picture this: if Nagisa's bloodlust was like a boulder that weighed you down until you could barely struggle to move, then this new bloodlust was like an entire mountain pressing down on you.

The eyes of the new arrivals snapped open and they looked around in confusion. Everyone's eyes were drawn to the source of the bloodlust, which wasn't hard, considering he was lit up like a Christmas tree. If said Christmas tree happened to be wreathed in crackling electricity.

Takaoka's eyes bulged, his mouth gaping for air. He felt like an insect that had been impaled on a branch by a shrike. Nagisa, meanwhile, seemed to relax ever so slightly when he saw who the bloodlust was originating from, surprisingly feeling a bit safer.

It was then that one of the new arrivals (probably a boy, everyone subconsciously noted from the voice) spoke up, "Killua? It's okay. We're fine."

Though the bloodlust still didn't let up, it seemed to lose some of the edge that was causing everyone else to struggle with breathing (it seemed like only Nagisa noticed that the new arrivals hadn't been affected by it in the first place, which he shelved for later), though Takaoka still gasped for breath like a fish out of water. Nagisa could only stare at his friend in awe. He hadn't even moved an inch, and yet had successfully immobilised pretty much everyone with his bloodlust alone. _'I've never felt such a strong bloodlust before. The only thing that could've compared would be the bloodlust Korosensei gave off when the girls were kidnapped on that school trip.'_

The white-haired boy stood at the edge of the helipad, hands in his pockets, electricity crackling all around him. He was trying to rein in his emotions so he wouldn't accidentally kill the bastard who had the gall to try and threaten his best friend and sister. Once he was fairly confident he could control himself, he shot forward at a speed which resulted in him disappearing in the eyes of everyone else watching, appeared behind Takaoka, and grabbed his head, shocking him into unconsciousness.

Takaoka slumped to the ground, eyes rolled back and frothing at the mouth. 

The threat having been dealt with, Killua seemed to slowly release a breath, the electricity around him disappearing. The new arrivals had stood up at some point, and the boy who'd called out to him before launched himself at Killua, screaming, "Killuaaaa!!!"

Killua caught him easily, as if he'd done this a million times before, and seemed to relax instinctually. However, this touching reunion didn't last long as Killua raised an arm and punched the top of the boy's head.

Tears seemed to appear in the boy's eyes as he drew back and spoke, "Ow! Killua, what was that for?!"

"For dragging my baby sister into danger, idiot. And for taking so long to come get me in the first place."

The boy wilted, but tried to defend himself, "I’m not smart like you Killua! I was panicking because you went missing, okay?"

At this point the girl, who was presumably the sister Killua was referring to, launched her own hug attack on the white-haired boy, who caught her just as easily as he had the other boy. She seemed to melt into him, a contented smile on her face as she spoke, "I really missed you, Onii-chan."

Killua’s eyes seemed to soften as he stroked her head. "Yeah, me too."

It was at this point that the rest of the class had managed to bridge the gap between the platform and the helipad—the only reason they hadn’t done so before was because there had been an unstable madman holding the antidote over their heads.

Karma was the first to approach, since he was the most familiar with Killua aside from Nagisa. "Yo, mind introducing us?"

Killua seemed reluctant, but introduced the two to the class anyway. "This is Gon, my best friend. And this is my sister, Alluka."

Karasuma had subtly placed himself between the new arrivals and the rest of the class, since he was unsure of their intentions, but hearing this, allowed himself to relax slightly. It was at this point that Korosensei spoke up, "Nurfufu~ And may I know where the two of you came from?"

Killua shot him a glare filled with the most killing intent that had ever been directed at Korosensei (which made the fact that he was in his invincible mode a lucky or unlucky thing, depending on who you asked).

However, before Killua could say that it was none of his business, Gon blurted out (like the idiot that he is), "Oh, we came from our world to look for Killua!"

You could almost hear the sound of Killua’s palm meeting his face as he lamented the fact that his best friend was a fucking idiot who couldn’t keep a secret to save his life. It almost seemed like everyone else internally sweatdropped as they thought collectively, _'_ _How honest.'_

Korosensei recovered the fastest, and it seemed almost as though those beady eyes of his had lit up in interest (though it was kinda hard to tell with him), "Oh? So you’re from another world then?"

"Yeah!"

"Interesting."

"By the way, how are you talking, Mr Ball?"

Luckily for Killua’s sanity, Karasuma cut off this back-and-forth, though he took that back after hearing what Karasuma had to say, "That’s not important. How did you get here?"

Having learned his lesson, Killua didn’t just glare at Karasuma—he also slapped a hand around Gon’s mouth before he could spill the beans.

"None of your business. Right now you should be worrying for your other students. You know, the ones who got poisoned that we currently lack enough antidote to treat?"

That successfully switched the focus of almost everyone back to the more immediate crisis. Nagisa had gotten up at some point and walked over to them, and now he looked a bit disappointed in himself for not managing to save the briefcase full of antidote, and now they only had the few vials from Takaoka, which wasn’t enough for everyone.

Noticing this, Killua walked over to Nagisa and patted his shoulder comfortingly. "Hey, it's fine. You tried your best; we'll work out a solution, okay?"

Gon and Alluka watched this exchange like the novelty it was; neither had seen Killua act this nicely with anyone but the two of them (even Leorio and Kurapika had to deal with more teasing than softness from Killua).

"No need for any of that." A new, yet somewhat familiar voice piped up. Turning, the class noticed the three assassins they had defeated before approaching, instantly putting them all on guard. Killua cocked his head. He couldn't sense any bloodlust from them, which probably meant they weren't planning on attacking, but just to be safe, he kept his hands on his yo-yos.

It turned out that Killua was right in that they weren't here for a rematch—they were just here to inform the class that they hadn't used the lethal virus that Takaoka had ordered them to use, hence the antidote wasn't necessary. After the three were taken away for questioning (with Takaoka having to be wheeled away on a stretcher), the class were wondering to themselves if this was what pro-assassins were like when they suddenly recalled the spike of bloodlust they had felt coming from Killua.

It wasn’t like they’d forgotten—it was more that their new guests had drawn away all the attention, especially after they learned they were from another world. Wait, that meant that Killua was also...

Though they all tried to be subtle, the sheer volume of glances alone was enough to alert Killua, let alone the fact that he’d been trained to notice when he was being watched. He knew what they were most likely thinking, but he deliberately ignored those looks. Luckily for everyone involved, no one was dumb enough to approach Killua with questions right now, especially after the glares Korosensei and Karasuma were given for those initial questions.

The journey back to the resort was relatively peaceful, if suffused with the awkward tension of a group of teenagers trying to hold back their questions. This didn't affect Gon though, who boisterously bounced around, asking questions, and generally worming his way into everyone's hearts like he usually did.

While the rest of the class gathered around their sick classmates, Killua brought Gon and Alluka back to his room, which was noticed by Nagisa (among others who were paying close attention to the now-revealed-to-be otherworlders).

Based on what Nagisa knew of Killua, the latter would most likely not want to let the other two sleep in their own separate rooms (given his protectiveness), but there probably weren’t enough bedsheets or pillows in his room, so Nagisa decided he’d bring enough for them just in case. When Nagisa knocked on the door to Killua’s room, he felt a bit nervous because maybe Killua wouldn’t want him interfering when he was spending time with his best friend and sister.

But when Killua opens the door, though he looked mildly annoyed at first, when he saw who it was, he seemed to relax. Before Killua can speak though, Alluka had already taken the bedding from Nagisa and insisted that he come inside.

Nagisa blinked and looked at Killua, who gave a resigned sigh before nodding. Emboldened by the permission, Nagisa entered the room and came face to face with Gon, who was stared at him without bothering to hide it. It was only now, under the lighting provided by the room, that Nagisa can see that Gon’s hair wasn’t black like Alluka’s, but rather had a dark green tinge to the edges, and his eyes were the colour of warm honey, a stark contrast to Killua’s usual cool blue.

At some point during their staring contest, Killua had shut the door and walked over to him, pushing him to sit in one of the chairs before speaking, "Don’t tell me you came just to give us some bedding. I know you have questions, go ahead and ask. Not promising to answer them though."

Nagisa rubbed the back of his head. Yeah, he could admit he was curious; Killua kept so many secrets after all. But the question he most wanted to ask was, "Does this mean you’re going to leave?"

Killua blinked, not really expecting that, and so didn’t answer immediately. Gon, on the other hand, jumped up from his seat on the bed and tackle-hugged Killua. "What? Not yet! We just got here! We wanna explore this world, isn’t that right Alluka?"

Alluka had finished laying out the bedsheets so she finally turned back to Nagisa. "Mhm. We want to meet all of Onii-chan’s new friends and see what his class is like."

At this, Killua could only give a little huff, having been clearly outvoted (nevermind the fact that he’d not really had any plans of going back where his family would be able to get to Alluka and Nanika for the time being—it was a matter of principle). Nagisa couldn’t help the feeling of relief that he felt. Sure he knew that Killua would probably have to leave eventually, but he was still happy to know the latter would be sticking around for now.

A thought occurred to Nagisa and he bowed towards Gon and Alluka, "I’m really sorry for not finishing that guy off and putting you guys in danger."

The two exchanged looks, while Killua just sighed and extricated himself from Gon’s hold to pull Nagisa up and gave him a reassuring pat on the head, this time seeming more sure of himself. "It’s fine. Not like they were really in danger anyway. I just overreacted."

Nagisa was about to say something but was interrupted by Gon and Alluka shoving themselves into his personal space to stare at him, as if looking at a fascinating specimen. "Er, is there a reason why you guys are staring at me like that?"

"Ignore them—"

"Thanks for being Killua’s friend! I know he must’ve been lonely!"

"Yeah, I’ve never seen Onii-chan act this nice around anyone except the two of us."

Nagisa blinked, not really knowing what to think about the sudden barrage of information after so long of having to decipher what sparse information Killua let slip. Now that he thought about it though, he really hadn’t seen Killua act the way he did with him with others, which kinda made him… happy? Was he selfish for thinking that way?

Grumbling, Killua massaged his temples before turning around, declaring that he was going to take a shower and that since they seemed to be getting along so well, he’d just leave them to it. All three of them noticed his slightly pink ears and exchanged looks, Gon’s and Alluka’s in particular filled with mirth.

Alluka was the one to finally point out the elephant in the room, "Bet you’re wondering about Onii-chan’s abilities, huh?"

Nagisa tried to shake his head and say that Killua could keep his secrets, but Alluka could see his curiosity.

"Did he tell you guys his family name?"

"Huh? Oh, he didn’t, he told us to just call him Killua."

Alluka muttered something under her breath that sounded like ‘figures’, while Gon, who had up till now appeared to be practically vibrating with energy, seemed as though his mood had been dampened somewhat.

"Well then let me give a proper introduction on behalf of my dumbass brother. He’s Killua Zoldyck, I am Alluka Zoldyck, and this guy here is Gon Freeccs."

Nagisa blinked, not really knowing how to reply, since it wasn’t exactly as if not knowing Killua’s family name was weird, seeing as Karma also preferred to be referred to by his given name, and so did Nagisa himself. So, in an effort to continue this conversation, he said the first thing that came to mind, "Was there a reason he didn’t want to tell us his family name?"

The two of them looked at him, both appearing as if they were contemplating whether they should answer, but seemed to find that Killua’s interactions with him had put him in the ‘trustworthy’ category. Gon was the one who spoke this time, "Killua… doesn’t really like his family. So he doesn’t really want to be associated with the name. I don’t blame him—I don’t like them either."

Nagisa recalled what Killua had told him earlier and could’ve smacked himself for not guessing this on his own, but Alluka’s follow-up turned his world on its head.

"Plus it’s kind of a habit by now to not declare that you come from an infamous family of assassins."

**Notes for the Chapter:**

> Yes, Alluka totally did that on purpose for the D-R-A-M-A. She learned from her older brother.


End file.
